THC Snow- don't want to mess up the harvest time

Through human error, seed gender selection, and drought my initial crop of six plants is down to one- THC Snow (and I lost 1/3 of it due to a drought-caused wilt). I guess I started it late because the plant did not start flowering until Sept 5; today (Oct 24) is Day 49 of the flowering period. I have read the flowering period for THC Snow is anywhere between 6-10 weeks, most sites say around 8 weeks is a good time to harvest. Today I noticed a few of the trichomes on the upper buds have a small smudge of amber; I couldn't tell on the other buds if the trichomes were clear or milky though they looked "glassy" to me. Sorry but I can't take picture but my jewelers loupe x100 makes it real easy to inspect the trichomes.

I'm looking for a head high, not much a couch-lock body stone, so:

1) About what percentage of trichomes should I wait to turn amber before harvesting?
2) Is a trichome considered "amber" if it has just a bit of amber in it or should it be full of amber resin?
3) Thoughts on harvesting the top part of the plant first and waiting an extra week or two to harvest the rest?

As always, thanks for reading and sharing insights

Personally i try to wait till de sugar leafes get amber trichomes, they get amber before the buds. That way you have max potency as the strain is meant to give and not influenced by broken down thc, cbn. But bud and flower appearance i look at too. You see when she is ready.