When should i harvest her ?

take a look at trichomes on calyxes. 10-50 percent or more.. personal preference. cola density pistil coloration and trichomes. use multiple observations to pick a harvest date. you'll be more consistent that way. Try early, middle and late. You can even stagger the harvest. Take off some top colas and let light penetrate deeper. Can try different ripeness if you choose too.

I would say she looks ready, myself... but you could wait another week if necessary. I harvested my OGKush on Day 84 so you're in the ball park! Good luck and congrats!