get a few grows under your belt, and do some experimenting... Let a plant go too long, chop one nice and early, take a sample when you *think* the bud is done, and dry it for a week to confirm, if its done, congrats, you gave it another week to fatten up, if not, you just gave it another week to fatten up. We see this question on the thread 25 times a day, if you need to ask if the plant is done, you really don't have the experience yet to challenge the answers despite what you've read and retained.