For starters, take in a few deep breaths and relax you're doing fine. There is no problem with any strain flowering before other strains because the "can't" until you decide. They will all continue to veg until you bring the light hours down near or at 12 hours. From there finishing up is easy if you have a strain quide telling flower times. I've harvested a lot of crops all at the same time even if a couple plants need another 7-10 days. The way I understand it - if you harvest a plant a little early you the plant has more of the THC effect and less of the CBD's. I could be incorrect on this last part, but my herb always is stoney enough for me so what the heck. If you want to finish them all off at their mature time, just cut them down as they reach their time.
Your next things to think about in future grows might be how to obtain greater yeilds by increased space, light, pots, air flow circulation, temperature control - the list never ends *)
