Well the majority of hairs i'm looking at are white and have not fully receeded.
7 weeks since you seen flowers or since you switched the light to 12/12 ??
Naw their are about 50/50 brown and white...their slightly receading so a week should finish em, but that is a good question. When do you consider start of flower?
The bud in the 1st pic does looks more ready then the 2nd that's for sure... you can do a staggered harvest, chopping whatever looks ready and letting the rest that needs more time, go for longer...