As someone who has been growing for 40 years, I can definitely say that stopping all fertilizers/supplements 10 - 14 days before the expected harvest date produces a tastier, smoother smoking and cleaner end product!
Keep watering in normal amounts and at normal intervals with plain water right up until one day before harvest day is just fine.
"Flushing" your plants with huge amounts of water is not needed and does not benefit the end result in any way.
Placing plants in complete darkness for an extended period, like 24-48 hours,is also ghetto science and not beneficial in my experience.
Same goes for products marketed as "rinse/flushing agents" for plants, just expensive snake oil...........plain water is all you need to use.