Remember too, not all strains of cannabis develop amber trichomes.
Harvesting a bit early is much better than harvesting too late while waiting for amber trichomes to appear.
Waiting too long means the plant gets closer and closer to death, and a plant closing in on death can not support healthy cannabinoids.
The amount of second grade over ripe pot that I see on this forum while people wait far too long for a mythical "30% amber" is depressing. Fine if you want dope that puts you to sleep, but most people I know like to get high, not drowsy and dreary. 10% amber is great pot.
Waiting too long for a strain that does not have the genetic capacity to produce amber trichomes will lead to harvesting over ripe pot.
Amber trichomes consist mainly of CBD, CBN and CBG, all these cannabinoids are non psychoactive, meaning they do not get you high, but they do produce a relaxing and sleepy narcotic effect. If you want peak THC, don't delay, harvest now and enjoy the fruits of your labor would be my advice.
If you prefer something that puts you to sleep, wait 1-2 weeks.
Why not harvest some now and some in a week and the rest in 2 weeks and find out for yourself what the different stages of maturity produce stone wise and then let those results guide your harvest timing in future, depending on which YOU prefer?
Hope this helps, Organoman.