Flush time?

Dr. Bruce Bugbee did a great talk about flushing a while back. They have found that you’re actually doing a negative effect in what you are trying to achieve by flushing. The final weeks are very important to the ripening of the Trichomes and if you starve the plant the nutrients to development those then you loose some potency and quality. The breakdown of chlorophyl happens extremely fast so the thought of keeping the plant starved the last two weeks will help but it has been proven wrong. A good cure after dry is the best and all that breakdown will happen the same regardless of a flush or not. I reserve a good flush to correct any issues I would be having in my medium. It’s a good way to “flush” out anything causing issues and resetting. Now if you want to feed the last week or two with just pH balanced water that is different than flushing. I always feed straight pH balanced water the last week since my plants are pretty much done requiring much nutrients at that point and any they need will be taken from what little is left in the soil and or plant material. I hope this helps.

When u see the first brown trichomes start flash for about 1 -2 weeks when they are about 20% brown u can cut

No. You still have at least 4 weeks to go........breeders descriptions are nowhere near reality. Once your plant has about 95% brown pistils is when "flushing" should be considered and then harvest 2-3 weeks later when the plant has 98-99% brown pistils. "Flushing" does not mean pouring gallons and gallons of water through the potter, just stop all fertilizers for the final 2 weeks before harvest and the plant will "flush" itself of any nutrient salts naturally.

Assuming you're talking about your AK47 diary....those plants are nowhere close to ready. Probably 3-4 more weeks at least. You didn't even really start showing flowers until week 7. Breeder's timetables are best case under the best conditions, generally they're a bit optimistic.