I used to check them too. Still do right at chop for the fun of it. didnt buy that little microscope not to fiddle with it!..LOL.. However, every time I look and say, "that one looks ready" the trichomes agree with me. The pic of all the tops was let go long for that strain and had more than 50% amber but I like that one a little narcotic.
The purple one in the other 2 pics is AK 47 with about 20% amber and 80% milky.
Nothing but dank buds comes out of my cabinet and I do not pull before they are done.
Hopefully this guy can convince his partners to wait. That looks like bud 3-4weeks into flower.