I FIMed once kind of by accident. A pnant about 6 weeks old in veg fell off my deck and got pretty mangled, so I whacked off the broken part, not even realizing I had left some growth at the cut. To my surprise, after a few weeks I had FOUR colas where just one had been. But...it took a few weeks of more vegging for it to heal and recover. Im not sure, but my guess is, it's probably better to let the plant veg until it's healed and you see the new shoots.
But I could be wrong. Im just thinking the poor plant is trying to deal with having been cut PLUS trying to switch to flower mode at the same time. Seems like a lot.
I know I would never TOP just before the switch. Same thing, kinda. Id let the plant heal and start to show new growth before flowering.
XW
CW