Tizoc
Member
You don't "time" her passive, it triggers the moment you use an ability and then you're stuck without it until your next ability rotation. I mean, don't get me wrong, it's a really good passive since it mitigates a fuckton of damage the moment you get in, but with Vi you want to kill shit, not itemize for it.
Rushing Warrior's means you get access to CDR + AD + Arpen before you use your ult, which means 15 seconds shaved off it's very long CD and a lot more damage to fuck up whatever you use it on.
I always build Warrior if I'm Jungle Vi. By time it I mean having an ability ready for use once her abilities are available, might be a poor choice of words, but I get what you mean.
Regardless, Warior+Trinity are my first items on Vi, then its tanking to unkillable levels.