Once almost all of the white hairs darken and begin to recede, don't be surprised if you see some new white hairs sprout. It doesn't happen ALL the time, but occasionally it will. If it happens in multiple places on your plant, give it a few more days. If it's just lower branches, you can harvest all of the 'ripe' colas and leave the few that still have white hairs a few more days or weeks. Nothing is carved in stone when it comes to 'how much time do I have left', the colas will tell you when their ready.
I tend to cut just the fully matured colas and leave lower, immature colas to develop a couple more weeks. Others may tend to cut the whole plant all at once. Neither is wrong, but cutting colas when they're fully mature maximizes your volume and potency. Why spend 3 - 4 months growing, then cut yourself short in the last 2 weeks?
If you want more input, post new pics around July 1st. Anything before then is probably too soon. And happy growing.