There are tones of people that do 12/12 right from seeds. the only down side to it is that ur going to get a significantly smaller harvest within roughly the same amount of time, people say that from seed to harvest on 12/12 only cuts maybe a week or 2 off the total time it takes to grow. Post up some pics if u can of ur larger plants, or at least some details. How big are they, how big is your grow space... If at all possible i would grow the 3 plants u have longer so that the WW has some time to catch up, after all a few more weeks to vegg will give u more budd on ur 3 plants and more bud on that WW