actually the "when u want" part is what kind of "high" the end user is looking for. If they desire a celebral, uplifting type high, the plant should be harvested when the trichs are mostly clear, maybe 20% cloudy. If they desire a bit of body stone along with that, then they would harvest when about 50-70% of the trichs are cloudy. for a full couch lock body stone, the trichs are harvested when you have at least 50% amber. but u should be flushing BEFORE that time, if u wait 2 weeks after they r 50% amber u r in the zone of loosing quite a bit of the thc, because u would be late harvesting the plant at that point. But I don't flush at all so that for me is never an issue.