Once they start rooting (roots appear) then transplant into the next pot. --you said they've rooted, so I would start using the 250w HPS once you transplant. your temps are good, what is the Relative Humidity? you wanna keep it kind of high during veg, around 55% - 70%. What kind of ventilation do you have? you're going to need some way of keeping the temps at 77 once you've got a 250w hanging 1.5 feet above. you're going to need a space secluded for them to grow, I'm presuming that you've got this already. I would personally plant them in 3 - 5 gallon containers while using something from Fox Farm, like Ocean Forrest or Happy Frog is good as well, but that is me personally.. organic MJ is always very nice when grown in the right conditions, when growing organic it's a little easier for the first few grows, til you really get the hang of it. I hope that you pH your water (adjust pH to 6.0 - 6.4 for soil..
keep us posted