How much longer?

That's still quite far away from the end, you know? Don't start thinking about flushing until most of those white pistols are going brown and the formation of white pistols slowed down dramatically, that's your flush period (if you even need/use one)

one plant is further behind.. i wouldn't even bother scoping trichomes. the calyxes aren't fully plump yet. This looks like 6-7 weeks of flower... 10-20 days remain, at least. The one with longer, white hairs is at least 3 weeks away... Sometimes plants can kick it into overdrive, but if the calyxes aren't plump, it's got time. I'm not a proponent of flushing, but your foliage looks a bit too lush... Dial back the dosage a bit... possibly just lower N and maybe Mg... a couple elements potentially contribute to dark green foliage as first symptom of 'too much' .. may take a little trial and error, but if consistent in how you do things, will apply to the next grow too.

hey 👋 close ; If I were you, I’d give it another 5-6 days, then do the flush, and wait another 3 or 4 days without water.