If you've never grown before (which I suspect you haven't or you wouldn't have asked the question), you will almost certainly run into over watering issues if you start in pots that large.
Start off with a small pot (solo cup, 1/2 gallon pot etc). After a few weeks, transplant them into your final pot. I start in one gallon pots, then transplant to the final three gallon pots during week five of veg. In total, I veg for eight weeks, and flower for 10+. 400W in veg, 1000W in flower. I have never come close to a root bound issue with those parameters.
When you go to transplant, just do it when the medium is rather dry. The plants will pop right out of the pots nice and smoothly. For the first water after transplant, water only about twice the amount of water you normally use so the roots start to stretch out, then after that, water normally.