Trichomes question

Once you feel it's time to check the 'doneness' of your plant from where, exactly, on the plant do you snip off a physical sample to view under a microscope?

The actual calyx. Don't use the leafs because they will look done sooner then the actual buds. By the way, a calyx is the part that the hairs come out of..

I take a tiny bud leaf, the kind you save for hash when you manicure the bud, from a few places on different branches. This gives you a good feel, but you have to be honest, especially with those lower buds.