There is a lot to learn from the pistils and calyxs. The cannabinoids obviously form in the resin of the trichomes. However if the plant isn't done growing the buds, why would you even think that it is properly mature?
Lots of people harvest early, and get high so they think they made the right choice. However they don't even realize how much more weight and potancy they would have gotten by letting the plant properly finish. I've done the side by side tests on a variety of genetics I've ran over the years. Letting the plants properly finish ripening, which includes letting the calyxs stop growing, will produce much better yield, flavor, and potancy.
Trichomes can show some of the maturity of the plant, but you shouldn't even look at the trichomes until the pistils receed and the calyxs start to swell. That final 2 weeks of swell is sooo important. Thats when the plant adds more weight, and finishes actually ripening.
With that said, the OP has at least 3 weeks left. All his growth is new fresh growth. These plants are still stacking buds, they aren't even close to mature.