changing nutrients when Flowering?

I think I'm ready to bud my babies. there indicas and are about 2' and have alot of lateral branching. I'm using general hydroponics' flora nova veg. formula and i'm planning to buy their flowering formula But I don't know if I need it when I decide to go to 12/12. or should I flush my soil with water for a few days. I'm a first timer and I have no one who knows about this shit.


PLEASE HELP!!!

i transplant into the final container at least 2 weeks before flowering. the new dirt has enough nutes to last a while for the transition and i just feed plain water. then the first couple weeks or so in flowering i keep up the veg ferts until the stretch is done and calyxs begin to appear. then i switch to bloom ferts.