I just move (not attack move, and only do this if you disabled auto-attack) in the direction first and then pounce. If they are just sat there doing nothing then you can atkmove , get up close and then pounce but you want to be really close in theory (chance of miss is progressively lower the closer you are). The other option is to lane with a stunner, I run veng a lot with slarks but anything with decent stun would probably do. I'm playing a lot of shadow demon currently and he's either fantastic or a huge problem as a pair - if the other person is erratic after the disruption then slark's going to have a hard time landing it.