OK, I've also been doing a bit of research into starting onions from seed indoors ahead of time. It seems the big difference is that in the southern areas, you don't get the long daylight hours that we get in the north during early summer (I guess this makes sense when you remember that in Alaska, sun's still up pretty high in the sky at 11PM). My source (which I can't find at the moment so this is from memory) said 12 hrs day/12 hrs night in the south. The long day onions which we're supposed to plant won't start bulbing until after daylight hours are longer than 14, but short day onions will start bulbing when daylight hours are around 12 when they're still much too young, and then finish growing alltogther, which is WAY too early for us.
What all this means is that when you're growing those long day onions from seed, you need to keep your lights on 12/12 schedule, UNLIKE the way you want to keep them at 16/8 or so for toms and peppers or even lettuce and crucifer starts which you (or at least I) would be starting in another week or so and growing at the same time as the onions (or some flower transplants too). In other words, you need to grow your onion seedlings isolated and under their own light schedule.... I'm definitely using one of my 10" clamp on lights with a CFL. If the area gets daylight, don't forget to synchronize your timer with the sun.
I'm thinking I've finally formulated my onion plans, so I'll most likely start those seeds tomorrow.