From the photo it looks like you still have a lot of fresh white pistils and the trichomes appear mostly clear. Most growers like to wait until those hairs have mostly darkened and curled in and the trichome heads are milky with some turning amber. That’s usually in the last couple of weeks of flower. Keep checking with a loupe or magnifier and start your final flush once you see the majority of trichomes go cloudy. Patience really pays off at this stage.
