Seems you don't forest as you don't get smite (too long else). Considering this, you CAN'T lane without Dark Wind. Even for ganking, this is the deadliest skill ever in early game.

Lvl 3 skill : 6 bounds -> 300 damage + 105% of AP on two targets. Including silencing them.

I often try to upgrade my 3 skills the same way, as they're all very usefull (and if i have to chose, i'd rather stop the drain at 3 and finish the 2 others first, more usefull in non 1 vs 1 fight).

I don't agree with waiting till late game with Dark Wind. You should take atleast one point isn't it silences the enemy which will make it very hard for them to fight back until you can fear them and drain. The fear range is bit short so dark wind is a perfect setup for it.