That sounds like a good way to stress out two plants to me.
I'd wait till I switched the photo to 12/12. It probably doesn't have the auto flower trait locked down in the seed, either the strain wasn't worked properly or you have a rare case. What strain are you using?
Or if it's getting way to big you could switch to 12/12 now and the if the photo hasn't shown preflowers it will keep vegg'ing until it reaches maturity.