You still got quite a way to go, at least another 2-3 weeks, perhaps more.
Start flushing when she has about 90% brown pistils and harvest when there are around 95-98% brown pistils, for prime cannabinoids and peak THC, and with a mind bending head high.
If you prefer a more drowsy, couch locking stone, due to degraded THC levels and elevated CBD and CBN levels, start flushimg when there are about 95% brown pistils and harvest when there are 100% brown pistils.
I flush for about ten to twelve days, meaning I give just plain water, nothing else for this time.
Making sure your plants are at peak maturity should be your prime focus, but having a decent flush is vital for a smooth smoke, so both of these things are of equal importance. It is easy/ok to flush a bit longer, as maturation can be drawn out, but timing the two together is a matter of experience and being able to "read" your plants. If you follow my suggestions regarding pistil colour and harvest timing, you won't be disappointed.
I have been judging my harvest according to pistil colour for more than three decades and find it simpler and more reliable than the "trichome colour method" which has many flaws in my opinion, as some plants will never develop amber trichomes and some strains will have 75% amber trichomes after only 4 weeks of flowering, with both situations being not ideal for deciding when to harvest.
Remember too, flushing does not involve drowning the bejeezus out of your plants, just give plain water in normal amounts, this is all that is needed.
The idea is for the plant to "use up" any residual fertilizer salts in its system, not drown your plants.
Hope this helps, Organoman.