like many subjects, people will complicate things like harvest. hairs do have plenty to do with harvest time, if theres more amber hairs, youll be getting more of a couchlock high than anything due to the THC degrading to CBD/CBN, white hairs means its still THC and you will probably get a more racy, energetic high, come curing time you can let them sit longer and let the THC degrade to CBD/CBN, although letting them run longer is better for trichs and overall potency, many have different opinions on what they believe to be time for harvest, so a big part of this is how you like your bud.
you dont need a microscope to determine these things, yellowing leaves usually appear around harvest time given the fact you dont feed them nitrogen up to harvest, this can effect taste in the bud. like monkeybones said, the more exposed parts of the plant and the closest to the light will be getting most of the energy, so chopping these first and letting the lower branches run is a good idea, i dont do this because im usually training them to grow equivalent buds, the goal is to keep them all at the same height so you dont let other get ahead. it looks like plenty of those hairs are still white, so like others said, let em run a little bit longer.
