Stuck where to to?

could thin it out if you think it is too congested. when decidingn what to remove in a congested area, favor removing anything the originates lower on the plant. apical dominance will cause such lower branches to get fewer resources than that above... ther may be soem rare instances you don't take the lowest off just to keep stuff spread out a bit better. I'd clean it up relative to the space you want it to fit in... expect a bit more growth after flip if you cut it back quite a bit... the root system is still capable of more, and it won't take long for regrowth to really kick in. 3x stretch in that context. trim down to the number of vertical colas you want... visualize a horizontal line where the larf starts and remove any lower branching below that point. get it nice and even and let it have 5-7 days to recover before flipping to bloom. So, cut it back a bit more than you expect, as you'll have another week of growth coming.

The plant need darkness so that it can go into budding stage 12/12hour cycle

Cut the main dominant apical and switch to 12/12 before it really gets out of control 😊