You don't need to gapclose if you're invisible. You can just walk into the lane undetected and position yourself so that they HAVE to walk straight into you. Ashe only threw volley in the direction she assumed you were coming from after the mark was dropped.
Her W indicator only shows where you are when it's full
You have to position yourself in the least obvious spot before dropping it. You have 2.5 seconds to move after that. All you have to do is stay juuuuuuuuuuuuuust out of visibility range, then strike the split second your charm is ready. It doesn't matter if the indicator shows your location because you're exiting stealth AS it shows your location.
You have to ask yourself "If i was the enemy, where would i run when i get the Eve mark?" 9/10 times, the answer to that question is "back to my turret."
If the enemy is overextended, you can position yourself between them and their turret. When you apply the W, they will walk straight back into you. If you do it right, the enemy will walk straight into your Charm+E+Qqqq combo with damage/cc from your ally.
If counterjungling post-6, get way behind the enemy jungler before you drop the mark. They'll be expecting you to come from the river/your side. If they aren't strong enough to 1v1 you, the natural instinct is to run backwards towards base.
For maximum ganking success, find a duo mid/top partner. If they play someone with hard CC, they can engage as soon as you drop the mark. Forcing the enemy into a 1v1 situation for 2.5 seconds while they KNOW a charm is coming. They basically have no way out, your laner holds them down while your W ticks away.
