I just grew out some Nirvana NL autos, I used CFL's, 24/0 pulled 2.5 zips from her. I used mixed spectrum 6500 and 2700 got the 6 packs from lowe's, about 10 bucks a pack.. I recommend at least 18/6, if not 20/4 or 24/0 You're going to sell your self short running an auto on 12/12. They aren't going to spike your electricity and this time of year, no heat. They already grow a little fluffy under CFL, going 12/12, I'd be afraid they'd be a lot less dense and it will certainly affect your yield. Remember, the biggest benefit of an autoflower isn't just that it finishes quicker, it's also easier to manage with lighting schedule and you don't have to worry about light leaks. Good Luck with your grow!