Okay, where to start.

Okay, your buddy has had it on 12/12 for 3-4 weeks. Now, that is the flowering cycle, and 3-4 weeks in, it should have buds forming on the plant. If there are no buds, it isn't flowering.

You can't switch the light cycle to 24 hours because 12 hours on, 12 hours off, IS the flowering period. You switch the lighting time, it will go back to the vegetative stage. That will result in massive stress for the plant, and will result in getting a hermi plant (both male and female plant matter, females are ONLY good for smoking). You get a hermi plant, that will result in seeded buds, and once seeds start to form, THC production stops.

So if it has buds and has been flowering for 3-4 weeks, keep it on 12/12, not on 24 hours as that WILL ruin the grow.

Second, it has been out in the natural sunlight, and you want to put in back inside, under some floro lights? No, that will result in stress as weel, and you could RISK turning the plant hermi. Changing it's environment will stress it out.

Changing pots in the middle flowering will result in stress as well.

To put this simple, if it's flowering and has buds, you don't want to re-pot it now, you don't want to change the light cycle, and if you do bring it inside, put it under HPS lighting. Floro lights are only really good for vegetative stage. You can flower with them, but it has been outside, and that transition could ruin it completly.

So I would find a spot and leave it outside and keep the lighting cycle to 12/12, unless you really want to mess it up.

Sugar won't help a growing plant as the roots simply won't take it in, plus it slows down the fert. process and feeding.

Ferts needed:

Vegetative stage: Something high in N (N-P-K) eg. 5-1-1

Flowering stage: Something high in P and K eg. 10-15-10, or 15-30-15