it's should be changing as he say's from clear to milky color, once you've got that, your good. Don't let too many amber color accumulate, as that indicates past ripe.
don't look at how much trichomes are on here, just look at how many are milky white, how many are clear, and how many are amber. I harvest often on the early side, so this should be pretty accurate, and about as early as you want to take it.
What I think I see here, is a few amber heads here and there, mostly milky, probably 80-90% and a few clear ones, maybe 5-10% or more. But, others here might have a different opinion.