What do you think for how long?

Hey! By the look of those pistils, i'd say she just started flowering. Harvest window opens when you start getting amber pistils. The best way to check is looking at the trichomes on the buds with a 60X magnifying loupe Clear trichomes haven't reached their full potency, cloudy ones are full of THC and amber are losing THC while gaining CBN. I harvest when after examining and finding 70% cloudy trichomes and 30% amber trichomes. For me that's a prefect combination, depending on the strain as well. With some strains I go with lower amount of amber trichomes but always attest 10%. This really depends on what type of high your looking for. As for what they look like, clear trichomes look like shiny glass, cloudy like plastic and amber like resin Hope this helped. Good luck and happy harvest!