m0useanswered grow question a year ago I am not a huge fan of flushing to the point where we deplete the medium with copious amounts of water. It does not do the things they claim it to do.
If you want more trichomes get better genetics, the more stress you put on the plant does not always equal better results. They can go hermi from stressors or foxtail.
Flushing does not improve bud taste, that is a myth and does not have backing, studies have confirmed buds that has been flushed have no more or no less "buildup" in the buds when compared via gas chromatography to each other. A technology that is far superior at detecting these microscopic differences within a substance. On top of this when given a blind taste test via humans senses they have seen that the judges "well seasoned smokers" can not tell the difference between a well cured bud that was flushed or not flushed.
You should decrease the feeds as the plants enter their last stretch of life before harvest as they are not using up the same amount nutrients in the medium. This is something similar that happens in the rainy period end of year. if you want you can give only water the last week of life to save yourself some money on nutrients go nuts, but don't water with runoff as the plant will be using the last bits up and starving it is not going to overproduce trichomes in this small period of time, this is done in its main life, cant create something from nothing.
If you lack a EC/TDS pen, confirm you are getting runoff if growing in soil less medium of about 10% every time and the buildup of fertilizer in the medium will be minimized. Work your way down to 1/2 then 1/4 the recommended dose of feed for the last 2 weeks of life. and it should be fine. I use a cheep TDS pen and it does the trick. fancier ones exist and some people just never use one. I like it for the diagnostic purpose to help troubleshoot things like this.
As for advertised finishing times. they are not always accurate. especially with autos as they can be quote unpredictable. keep an eye on the plants growth/pistils and trichomes for indicators of when its ready.
Good Luck!