Cannabis does not need any darkness during veg. That is a myth. Your *environment* may need the 6 hours of downtime, usually due to inadequate ventilation, to provide some time to cool down, but the plants do not. 24 hours of energy beamed at them during veg just makes them grow faster. If you don't like the speed at which they grow and wish to slow them down, or your ventilation/temps are inadequate to handle 24-hour lighting, then 18/6 makes sense.

As far as transplanting goes, I usually don't transplant until after I know the sex. Why waste growing media/soil on a male? When you do ultimately transplant, get some Fox Farm Ocean Forest soil, and use that in the new pot. I wouldn't use Miracle Gro ever again. I tried it once, had some probs. It doesn't even *look* like healthy soil, especially when you compare it to Ocean Forest, which is just the most awesome soil I have ever seen.