m0useanswered grow question an hour ago I'm not a huge fan of stagered harvest unless the plant is massive, and by massive I mean like 6feet tall outdoors and wide as a redwood cedar.
But if you want to do it. try it.
My ideal for amber is 10-15% the lower the better IMO.
The more amber it has the more sedative the weed will be. So if you want something for sleep then yea, wait till is 75% amber but its gonna knock you out. the THC starts to degrade into CBN and CBC.
Just based off the pic this plant is ready for the chop now. If you do staggered harvest vs whole plant, just try and dry the harvested bits in a cool dark location. The main plant might stop growing from the shock and just ripen up fast. I often find its not worth the extra effort and time of one week this stuffs ready for the cure jars and the other is waiting more.
Good Luck!