IV been wondering about this too. Last year I grew a white widow cbd auto along with the regular thc strains I always grow and did harvest when I started seeing a little amber. the high was very heavy and when mixed with a couple of beers made me dizzy which normally doesn't happen. I think if you wait to see some amber before taking a cbd plant you get more CbN than cbd. I'm going to email a friend who works for a CBd hemp flower company and see what he says and I'll let you know.