Diary of a beginner who needs help

Definitely veg and train them more before flipping :)

When you switch to 12/12, the plants will stretch 2x-3x there current size so you want to make sure you flip when they still have room to grow 2x-3x and still be at least 18"-24" away from the light at the highest it can be in your tent. You might be able to top them and train them a little wider for more yield, just don't let it get to crowded in there. Next grow, you can get the same or more yield with fewer plants. Growing less plants and Using a technique such as SCROG will allow you to fill the whole tent with only a few plants. It will save you seeds and yield will be the same since more plants doesn't allow for much training.

are they photoperiods? do you want to initiate flower phase? Then, yes, that is required. use pot elevators (container,not weed-pot, lol). Use some old milk crates or buckets etc.. raise it up to the same height and all is well. fill the space properly before flipping, even out the canopy any way you can after that is acheived. If the are is roughyl 70% of Length x width dimension (~49%) it should fill in after flip. You'll have at least 4 more weeks of strong vege growth coming and sometimes more. less light = less growth.. i'd hesitate before choosing that route.