No.

You should stay at 12/12 and let it finish unless a) you are just DYING to force some herms or b) you are putting it back in 12/12 to reveg for at LEAST 3 weeks and take cuttings.

Remember it is stil going to grow.

When you put it back in veg, just do it. Nothing fussy, no transition (that is even more stressful, since you are almost GUARANTEED to turn on the lights late or whatever a couple times). Just stick that thing back in your veg room. IMHO you should not try to flower it at all for now, just take clones and flower THEM, and flower the mother down the road when she gets too big.