Shagrathanswered grow question 5 years ago Hi!
You should not have anything to worry yet. They will probably about double/triple in height when flipped to flowering. So if they are 12" now when flipped they became max 36" and you still have plenty of room between the lights and canopy. Just keep them as horizontal as possible and fill the whole area before flipping to max yields!
Btw I should pluch some leaves off from the bushiest, that's too leafy IMO