Have they all gotten their preflowers yet?
Imho I'd wait for a majority of them to have sexed themselves/gotten preflowers, meaning they're sexually mature.
They won't flower before maturity anyways.
Roughly around 30-40 days being typical in my experience.
Some earlier, some later. Lol.
I would only suggest flipping now if it were hydro, if you're wanting to get a more than respectable yield. I think toughing out until at least a foot tall would be a good time. That would leave you with about 41" head space left (to the lights right?) so if it doubles in stretch to 24", that's another 17" of head space, which would be a good distance from the lights. You're pretty close already.