Things you can use to determine you favorit harvest point --
1) Trichome color -- there is a lot of misinformation out there that gets repeated that contradicts reality as proven by real world measurements (see link below). First, clear trichomes do not ever mean it is low or devoid of THC. A smokey trichome is actually the initial stages of degradation, so it is absolutely not "peak thc" for a trichome as that makes no mathematical sense nor is it backed up by real world tests. For the most part, if your goal is highest THC% (this isn't a suggestion), you should harvest 1-2 weeks before most people suggest in regard to "50% amber" or whatever. This is not a suggestion. there are other factors invovlved, like yield. A few lost fractions of a percent while gaining enough weight is obviously worth it for most people, but technically speaking, peak THC will be long before most people suggest that you harvest... again, proven by real-world testing of suitable sample sizes.
2) Pistil colors... toward end they should change color and retract.
3) Bud density... I don't suggest being overly handsy with plants.. better not to touch and fiddle like an enamored 3-year-old, but a little squeeze here or there in a limited manner isn't going to rub off too many trichomes or damage the plant.
4) Rate of drinking... toward end (senesscence) it will drink less... in my expereince it happens all of a sudden... be feeding every 2-3 days at same resulting pot weight, then all of a sudden it takes 2x or 3x as longn for it to drink same volume of water. my temps and RH did not swing drastically to cause this.. the plant just slows down uptake regardless of current VPD remaining mostly consistent.
Most importantly, try different points within a harvest window... it is not just 1 day you "should" do it.. but there is probably a 2-3 days window that you will prefer over others.
There's a lot of shit going on inside the plant that we don't have mapped out and one of the worst ways to measure this sort of minutia is relying on other people's senses that lack the necessary resolution or simply their feelings that lead to unproven beliefs that some portion will cling to because it is intrinsically linked to their egos instead of just accepting reality. We all believe in something that is wrong at any moment... when faced with incontrovertible proof otherwise, those that cling to bliefs are just mad as a hatter. It should not be a bruise to the ego to be wrong about something.. shit happens. assimilate knew knowledge and move on. simple as that.
Don't focus on the technicallity i mentioned about peak THC% above. Use all three metrics to find your prefered harvest window. Trial and error... after a few harvests you'll better know what you like. TBH, you really can't go wrong... bout the worst you can do is cost yourself somem small % of harvest weight or maybe wait too long and the damn thing dies on the branch. LOL.
Give this following link a good read... it turns a whole lot of myths on their heads... highlights some groupthink that is occuring in this market:
https://www.scirp.org/journal/paperinformation.aspx?paperid=93052
-- the people behind this are acutely concerned with ROI... in this case it is a good motivational factor to map it out correctly as opposed to generally accpeted and mostly unproven hypotheses.
Before reading that i was hell bent on trying "later" harvest windows with more amber. Everytime i harvests earlier it turned out better, LoL. It tasted better, i enjoyed the high more etc etc. Heck some plants never turned amber for me.. can wait until it starts to rot on branch before i see it. Some of that is personal preference, too. There's a wide range of "acceptable" here... don't get caught up in what others do beyond a very generalized suggestion.
what about the trichomes that have been covered up by layers of calyxes... our eyes simply cannot resolve theses things. lab testing proves how wrong initial perceptions were and that should reinforce what i am saying... ppl believe things that are batshit crazy and enough people repeat it, it becomes a "truth"
**"Groupthink is a psychological phenomenon that occurs within a group of people in which the desire for harmony or conformity in the group results in an irrational or dysfunctional decision-making outcome." --- this is a rampant phenomenom that permeates all cultures of the world.