It’s definitely too early to start a flush. I see what you mean about the trichomes but these still have a lot of time to go.. I’d say 2-3 weeks.
Now, if you’re doing a flush where you do no nutrients, you only need to do that for 3-5 days in DWC .. 7 max if you want to force some fade.
I personally don’t flush this way.
I taper my nutrients down for the last 7-10 days and on chop day they are quite low (0.5-0.8) but not totally depleted as a lot of folks do. I believe this is a better way to go about harvesting. But everyone has their own opinion on it. Tons of ppl still do no nutrient flushes.
Either way, DWC starves the plant much quicker than other mediums. So like I said 3-5 days is sufficient for a flush. This is nice because it allows you less of a guessing game as to when to start. Once all those are as milky as possible, and you see hints of Ambers coming in, as well as 75-85% of the pistils are browned - then you start that quick flush and harvest within 3-5 days (or 7 if ya want a super long one)
Hope this helped. Nice grow - ETHOS are spectacular genetics I just finished up planet of the Grapes.
Good luck