, if one chopps a plant with clear trics, one will have chopped an imature plant, and if one chopps a plant full of amber, plant has been dulled out by overripping, so optimal harvest is when all trichomes are cloudy, and that is verry rare! ... usually when 90% of the plant has cloudy trichomes, 10% has already past maturing point, so a bit of amber is a good indication of proper harvest. not to mention that when trics go amber, THC oxidises into THCV CBN, and other cannabinnoids.
Very long discussion on this here if you're interested in learning more from a bunch of very motivated sativa growers: https://www.icmag.com/ic/showthread.php?t=271153
In short though I would say in my case I rarely see frosty trichomes on Ace sativas no matter how long they grow. They turn clearish amber when they are way overgone and the trichomes are all withered looking and bent over / shrunk. Way beyond a good harvest point.
I think the best way is sample early and often and keep the samples separate and try them after curing and at least a month of storage to get a better idea of what is best for you.
I've found consistently after doing the above that the best harvest window is when the pistils are 50% dead or slightly more in all my strains but maybe that's just my conditions.
In every strain when the pistils are all dead I note always a very dull cloudy headed uninspiring high that only gets worse on long term storage.,