At this stage, your plant is well past her prime maturity and peak health, as evidenced by the complete lack of white pistils and only brown withered pistils present.
By now, your plant has been going through a lot of THC break down into CBD and CBN, the non psychoactive cannabinoids. Harvesting now will give you flowers with a heavy sleepy and lethargic stone with very little actual high. The breakdown of the THC occurs due to the plant being close to death and because of this, her metabolism has also nearly stopped, meaning there is not enough energy to replace THC faster than it is being broken down into CBD and CBN, resulting in flowers with lowered THC levels and elevated CBD and CBN levels.
This may be fine if you prefer couchlock over the clear, psychoactive and inspiring THC type of high, but if you want a THC uplifting high, next time you will have to harvest earlier, while there are still about 5% of whitish pistils remaining on the flowers. Judging maturity solely by trichome colour, is in my opinion, misleading, and judging maturity by pistil colour is a far more accurate way of being able to judge the plants stage in ripeness, for pistil colour will reflect what the plant is actually up to, chemically and physically. Once all the pistils are brown, the plant is on the verge of death, making cannabinoid quality a redundant consideration. Some cannabis plants will never develop amber trichomes and other strains will have 50% amber trichomes at 4 weeks of flowering, some 4-6 weeks before peak harvest maturity.
Sativa or sativa dominant plants are known for amber trichomes in greater quantity and earlier than indica or indica dominant plants. It is believed the amber trichomes of sativas is an adaptation to the greater amount and strength of sun in the equatorial regions, where most sativas hail from.
I would be harvesting this plant ASAP and a one week "flush" would be more than adequate. Waiting another week would result in more THC breaking down and it is all down hill for this plants' cannabinoids at this stage of maturity. This may seem harsh, but it is what it is.
Hope this is of some help,............
Organoman.