I have read that the 30x and 60x Jewelers loupe are what to have. I have a 10x , not strong enough. The 30x dia. is I think 21 mm. and the 60x is really small. I just found a 40X loupe with a LED light That is 1 inch (25mm) in dia. for $9.99 I will get it Monday. I think that will be great.
I think it all depends on how full your jars are, if they are full, let it ride, if not start chopping. lol
I use a loop and I have a couple of digital magnifiers, its taken me some time but now I only use the 30X glass. I want to see what the whole neighborhood without peaking in the windows. The color of the many out weighs the few.
I use a LED 30x 60x eye loupe. its not easy! what works best for me is to cut a piece of bud that you suspect being ready. Cut it off and take it into some natural light so you can give it a good evaluation. What im looking for is mostly cloudy (80%-90%) with a bit of amber. Clear trichomes arent ripe. You want to look at the bud itself and not the leaf. And check the whole plant overall. Reading trichs is kinda an art and you get better with experience
Also, all though a few of my weedportal members may disagree, If you start your counting upon first seeing flower, you will be very close to the breeders flower time