I've got these 4 plants in 1 gal pots, that's what I intend to keep them in, judging by their size about how much longer before I should start flowering them?
Should probably start ASAP man, if you're really determined to keep them in the 1gal. Don't wanna let them go too long, fear of getting root bound.
Personally, I would. They look old enough and you can't run them much longer in those pots. You still might run into root issues even switching now.
Can you see roots coming out the drain holes? Do some research on "root pruning" I've seen a couple grower do it while growing in solo cups.
u would have to put them in bigger pots if u were worried about the roots u should start flower now. all u need to do is give them 12 hrs of darkness and 12 hrs of light from now on