Well with that extended release crap you might run into problems later as it makes it harder to control the amount of nutrients your plant gets and often results in burn. When they get big enough to transplant into larger pots I would put them in some potting soil that does not already have ferts in it. And the 12/12 light cycle is going to make them flower super early if that what you want. If you want to veg them out and get a decent yield put them on 18hrs for now