Find a few champions you're comfortable with, and then start playing PvP soon. When I first got into LoL, I spend around 2-3 years only playing bots, because I was afraid of the toxicity everyone kept talking about. The first week in PvP I learned so much more than 3 years of playing bots. I regret not starting to PvP sooner.
The AI of bots isn't really that good. You can easily bait them into overextending and subsequently kill them. It will lead to learning the game wrong, because things like that don't happen in PvP, so it gives a false sense of how good you are. This also means you will develop a relatively aggressive playstay, which is generally not so good when you're new to PvP. I'd suggest to play safe during your first few games, and then you can become increasingly more aggressive, until you have found yourself a good balance. That said, bots are great to try out different champions, so you can get a feel for their abilities and general power curve.
Also, people just love to talk about how toxic the community is, but don't let this bother you! It was the reason I refrained from playing PvP for so long. Once I start PvP'ing, I barely noticed any of the toxicity that everyone kept complaining about. It's mostly just a hyperbole.
Final note, if you have a friend to play with you can try to form a botlane ADC/support duo. It may make the game a lot more fun.
And remember, most important of all is to have fun!