Hello \o yeah most skills hit you by the time cast bar ends not when the animation hits so it's good idea to get out before it fills, as soon as you see it filling, move.

But not all skills work like that. For Example, the bombs in titan HM don't show a AOE around them so there may be times when you think your out but you could still be in it and very rarely have I seen skills go off 1 second after the cast bar fills, the only time I can think of now was the T12 Raid black fire, when the cast bar filled a Black fire would appear beneath your feet 1 second after it's cast.

But all in all the main thing is moving out before the cast bar is done. You'll get the hang of it ;p