Sence your growing in soil, Ull want to flush for about 1.5 weeks.
Flushing doesint mean over water though. still be carefull about howmuch you water as overwatering at this point can hurt the bud : /
water your regular amount with pH balenced water (bottled water will work just fine, its balenced at a perfect 7.0)
So for amount just do your normal amount that you have been watering and as for how often, you should also do your regular watering schedule. (about every 3ish days for me) but at least water 3-4 time before harvest.
Also not completely flushing will not totaly screw up the grow. It doesint effect THC level, just how good the smoke taste. so if you start to see over 50% of the Trichs are amber, then go ahead and clip.
But she does look like she has about a week ish left, So id go ahead and trim those big fan leaves off(keep the smaller leaves) and start with the pure H2O on your reg. watering schedule : )
And your welcomes ask all you need to, theres no such thing as too many or stupid questions! : )
Laters
DaCDaC