trichome color
pistil color
density of buds
Use all three to determine your preferred harvest point. The info out there is unsophisticated at moment. You got people assuming things without any lab equipment to prove what they are saying is true -- just like the whole "end of harvest flush" reasons that have been proven untrue, then they rush to make up new reasons that weren't important before but now are once the old reasons are proven wrong, lol.
clear is not devoid of THC. Cloudy is not "optimal" THC. Some plants actuallay have a higher percentage of THC a week or so before the have ripened up fully (i.e. better yield, but slightly lower %). Some are reaching max potency right on time... this is what empircal evidence has shown using lab equipment testing samples of plant material for % of mass of the psychoactive molecule.
So, i would suggest trying early, late whatever... until you find the high you enjoy, and know that some plants will vary a bit how they develop at the end.
There are plants that simply won't turn amber very much... it will start to rot on the branch before you ever see "30%" amber.
Second, this info is based on physical observances of the outer layer. I bet if you scoped and inner calyxese (?plural?) that was covered up long ago it's amber AF. That's a guess... But, if you only look at the surface and assume things about the entirety, that's a dangerous assumption that leads to easily avoided falsehoods... and if it is quite a bit amber in there, it tosses the previous reasoning on its head... not unlike the empircal evidence proving flushign to be a figment of grower's imagination (as far as end of life flushing before harvest... flushing is still a good tool for big toxicity problems).
In the end some amount of clear/cloudy and amber is most likely the "optimal" point... but, i'd just suggest exploring the range of possibility before locking into one thing and assuming it. I don't think it'll be wildly different than anything you find on google or in these questions, but keep an open mind so you can find what you prefer and not just some badwagon of groupthink.
Later harvest is supposedly more sedative in effect. Early harvest is more "speedy"... Maybe you only care about yield and a few lost % of THCa/THC is no big deal. There are lots of perspectives that lead to slightly different individual answers. Use this info as a ballpark only. Trial and error... in time it will be comfortable. Early on it's "greek"