Three different plants, I’m looking for optimal harvest time. (A,B,C) I’ve heard the pistals should be browning, is this enough?
You can tell better if you look at the trichomes. You will need a jewelers loop or one of those microscopes. How long have they been in flower? 
You have a ways to go. 3 weeks or more IMO.
What change in the tricombs am I looking for? I have a loupe. I didn’t write down when they started to flower, sadly.
Nevermind, someone posted a chart. I’ll wait for opaque with some amber. 
Don’t get triggered, as I have twice, by the presence of initial 1:15 amber trichromes and stamen hairs that have mostly turned a color. The amber trichs will only very gradually increase in ratio on the ovaries/calyxes, while a lot more whiteness everywhere adds serious dry weight density in the next weeks, at least eight days, before the ratio begins to change. The sugar leaves and even an occasional calyx may have some amber trichs from the initial onset of milky-ness, in my outdoor opinion, and therefore may not be an indicator of any time for harvest. The pistils may all go half-white/half-tan/pink, and then all tan, and then half orange, and then half orange/brown, before density is measurably different. I have mistakenly harvested three times now when i saw a darkening of stamens, a 1:15 presence of light-amber trichomes, a majority of milkiness which was probably the low end of milkyness, and a propensity to be done with the waiting and louping process, … which dried into beautifully large larf nugs. I was shooting for racy versus couchlock, but this stuff is young.
I feel I wanted someone to tell me that what initially may appear as ‘within the window’ is only the starting gun for a minimum one week and maximum 8 week additional wait. I feel squeeze testing for density can help, also standing far back and looking at the whole plant. Still, I see a lot of dense mature buds on these blogs coming off of plants that still seem quite vibrant and green, go figure 