If all the pistils are brown, time to harvest.
Your plant has now passed its peak of THC quality and this example shows how judging maturity by trichome colour alone is not the whole answer.
Some strains will NEVER get amber trichomes, so waiting for them could mean a half dead plant, before harvesting at the last minute out of panic that the plant will be dead soon, so I better harvest now, before she IS dead.
At this late stage most THC has broken down into CBD and CBN, meaning there will be a reduced "high" effect and an increased "stone/sleepy" effect due to the elevated CBD and CBN levels and the reduction of the THC level.
Hope this helps and harvest away! , ..........
Organoman.