i will take that 2 cent if u dont mind, cause i herd something about bitter smoke and waz hot sure why, now i no thank u much.many good grows 2 u. thanksmy advice would be to start flushing around 1 week from harvest.. but theres a large range of when to flush, if your soil drains/drys fast, you could prolly wait and flush <1 week before harvest.. if your soil dries/drains slowly, you'd be better to flush earlier..
flushing a few days early wont affect the outcome of your buds too much as you've pretty much reached the max bud size/potency/etc.. but flushing too late wont be very effective and it will give a bitter smoking bud.. just my 2 cents,