There are no junglers who require a leash, so the leash aspect you outline as a concern is a non factor. If you don't know how to do a leashless start at any camp and claim two whole camps without a leash of any sort you need to consider that you do not understand how to jungle very well.
There are not a ton of players who actually visit the boards, so this information I am about to divulge is actually not that common throughout the community but it I am about to share my greatest secret to being a successful jungler in league of legends. I don't kid, I am not exaggerating, if you follow the advice I give you here you will see a DRAMATIC increase in your win rate from this particular role.
Here it goes. You guys all know this item exists right,
?
It's the single most op change ever made to jungling. It completely redefined the champions capable of being successful in the role. Literally EVERY champ in the game can now jungle successfully because this item exists. It doesn't matter who you want to use as an example, I can do what I am about to explain to you folks with Soraka with no runes because this item exists.
Here's the run down: When you open a game as a jungler in solo q always, always, ALWAYS, open in the opposing teams top side buff. Invade with your mid and top for safety to make sure you don't walk into an ambush. Have your bot lane watch your bottom half jungle. 99 times out of 100, even in diamond level play where I STILL do this every single time, the opposing team jungler will be starting on the bottom half of their own jungle. Starting at his top side buff presents you with an opportunity to open each game in a consistent fashion, using the same pattern, to acquire and early lead for your team that tends to snowball itself.
Firstly, you are starting on the opposing team buff, so you will deny the enemy jungler 2 camps on the top half side of his jungle that will deprive him of experience. You can do this with no leash, a fast leash, or a full leash from the top laner, but preferably no leash so that you can set up point number 2. Point number 2 is that doing this with NO leash at all gives the enemy team ZERO information on where you started as the jungler yourself. This means they have to anticipate that you could have started ANYWHERE since they didn't see you get a leash from the bot lane or top lane. This confuses the enemy team and will afford you an opportunity before the 3:30 mark in the game. After you complete the buff and the small camp in the enemy junglers top side half, back immediately. Buy a hunters pot. By the time you have done this it is usually about 2:30 seconds into the match. Most enemy junglers will be JUST completing the first half clear on the bottom half of their jungle, invading into your bottom half jungle, or moving to the top half of their own jungle. This is vitally important. It means you are now the person dictating the pace of play and the opposing jungler has lost the initiative as no matter what decision he makes next it will be an ineffective decision.
Why? Here's why. You KNOW what he is up to. He has only the three aforementioned options as to where he can be and what he can be doing. This is why he has lost the initiative, as the opposing team, since they didn't see your start, have NO idea what you are doing or where. As you purchase your hunters pot head to your own top half jungle and secure your second buff, this should be completed by the 3:10 mark in the game, you will have full hp when you complete it and a load of extra potions as well (the enemy jungler will have no pots of any kind remaining unless he TOO does what I am telling you folks to do). On you way TO that buff you need to make certain that your bot lane is aware of the possibility of the opposing jungler being in your bottom half jungle uncontested and make certain they put up the wards they need to avoid being early ganked if did he choose to wander over and invade. This will make certain that even if he has invaded and you are trading the top half of his jungle for the bottom half of your jungle he cannot get a strategic advantage by also being able to gank that lane when you are not capable of responding to the gank yourself. You also need to notify the mid laner that he could be in danger and needs his ward in the bottom river bush to avoid being early ganked. If you do this you have completely invalidated the opposing junglers actions for the first 5 minutes of the match or more as he has nothing he can do except power farm that half of the map. If the jungler has opted to move to his top side jungle then you have an even greater advantage. Once you complete the taking of your second buff at 3:00-3:10 you know the enemy jungler, if he isn't in your jungle, is finding out that you too most of the top half of his jungle so he has nothing to farm except a gromp. This forces the enemy jungler to make one of two choices, take the gromp, or immediately go for a gank in top lane at 3:30 with only one buff instead of two. After you have completed your second buff you, too, have a pair of choices now. You can gank for mid lane, or top lane, with the strategic and tactical advantage as you will have superior health and buffs should the opposing jungler happen to mirror your move. 9 times out of 10 the best bet here is to gank top lane at 3:30 into the game. This is usually the easiest enemy laner to kill and the most impactful kill you can make on the map at this point in the game as top lane is a long lane and the nature of top lane is extremely snowbally with the first kill often deciding who wins or loses in that lane. If you are following this step by step process I am laying out then the vast majority of times you will be arriving in top lane, at 3:30, about 15 seconds ahead of pace of the enemy jungler (unless they have just ridiculous clear speed) and you will be able to secure first blood an overwhelming majority of games. Afterward you have the option to chain gank into mid lane and then into bot lane, or farm your own jungle on your way to mid for a gank, then farm the bottom half of the jungle on your way to a bot lane gank.
If done properly this style of open will result, consistently, in the same set of circumstances: 1) the enemy jungler is now behind in experience and income, making him less effective. 2) you have acquired first blood gold for the team and secured a lead already in one lane which you will likely never have to return to for the remainder of the game allowing you to focus your ENTIRE efforts on only one half of the map, allowing you to better control the portion of the map with the greatest concentration of objectives. 3) You have secured a 3 buff start for your team. You can give an early blue to your mid laner if you choose, or you can take it to hit level 6 about a full minute before the opposing jungler will be able to hit level 6. 4) you have dictated the pace of play that the enemy jungler must abide by since he is behind, he has only limited options and all of these are now responses to YOUR actions as opposed to proactive actions on his part. An enemy that you force to react to your moves is an opponent that is on the back foot and can easily be taken advantage of. 5) This style of open protects your solo laners early in the game, the most vulnerable lanes, because you will always be in position to quickly react to and assist your solo laners based on how the lane matchups are going. 6) This style protects bot lane significantly better than any other possibiility in the later portions of lane phase (post 5 or 6 minutes) and throughout the mid game because you have set up a circumstance where you only have to pay attention to half of the map since you already acquired a huge lead for the part of the map you are not around as much. This makes it easy to put your bot lane in a position to be super effective in the mid game and late game while simultaneously offering an extreme level of control over drakes and when they can be taken.
No joke, if you start like this every match (and yes, sometimes you and your invade crew will get spotted out and you'll have to retreat for a different start, but most of the time you will be able to manage this open) you will quickly find your win percentage skyrockets because this is the most fundamentally sound opening for a jungler and has been for more than 3 seasons. The ability to rapidly and dramatically acquire significant advantages for your team that lead to a snowball in the first 4 minutes of a match is the most consistent chance for success game in and game out.
In other words, if you ever started bot side, with a leash, ever, then you were doing it wrong anyways. If you open each game the way I describe you put yourself in the driver seat before a single player has killed a single minion and never have to relinquish the wheel. You will be able to dictate the pace of almost every single match you every play from the role and win at a prodigious rate because this is the most fundamentally sound opening for junglers that has ever existed. 60% win rates? Sure, ez pz. 70%? Oh yeah, very doable. 80% win rates? Yeah, if you are extremely good at organizing your teammates and communicating strategy win rates in excess of 80% are very possible because of the consistency of this starting pattern that results, in excess of 90% of the time, in first blood for your team, an enemy jungler who is behind, a three buff start for your team, and complete control of the map.