Why would anything be different? if your fertiization procedure was maintaining a healthy plant, simply restart what you were doing before, or make necessary adjustments if it was not maintaining health.
Flushing doesn't actualy impact the buds in any meaningful way. Flushing the substrate does not 'flush the plant' or anything like that. The plant has absolutely no process for excrection and no anatomy that can carry out that function. it is shit people made up that never took a biology class in their lives. It's retarded dogma with no evidence to support.
giving water only at the end can save a bit of effort and time, but other than that, there's no reason to do it for the plant's sake. Just make sure the canopy is strong enough to do such a thing, otherwise you are just needlessly hindering a plant and reducing potential of outcomes.
There's a lot of personal preference that goes into when to harvest. This look a bit too early even for me, and i prefer an earlier harvest window. The calyxes have not fully plumped because the hairs still look a bit long. Trichomes are your best observable trait to use, but pistil coloration/dying off and nug density are 2 other observations that can help keep you on track. just find a way to be consistent and then you can try different points in the harvest window to figure out what you like best... early-to-late.