I don't recommend doing your harvest based on a set time frame. The buds will continually fatten up until about a week from the harvest date. Really pay attention to the trichomes though as they are the absolute best indicator of when its ready to harvest. You are looking for as many trich heads to be cloudy. Most times this requires some of the trichs to go amber. At the end of it all the ratio of cloudy to amber that you go with is a lot of personal preference and partially strain dependent. Some people go 90% cloudy 10% amber and others go 60% cloudy 40% amber. If you want a more heady racy and energetic high harvest with a lower amber %, but if you want more sleepy, relaxed, and couchlock then go with a higher amber %. The more cloudy the more THC. The more amber the more CBN.