With regard to trying to time it exactly right - I once intentionally let a grow go extra long just to get a sense of what was too long (that's my story, and I'm sticking to it). Based on that, I'd estimate a 3-4 week or so harvest window for a typical 90-day auto.What do you guys think??? Is It time to chop?
Early/late within that window is a matter of preference based on how you like your buds, how well you can convince yourself that you can determine the perfect time to harvest, and how long you can convince yourself to wait.