You should give the seedlings at least a 7-10 days to get their rooting established and then they will get going on their leaves...at that point you can move them under lights (reduced if possible, about 20" above).
If you type "Seedlings and Lights" in the Search Forums you can begin reading up on your options
I veg seedlings for 2 weeks from breaking through medium, then move onto placing them under MH bulbs, so i either wait till the 3rd/4th node or the 2-3 weeks from breaking medium.
Depending on how many plants you have, 1 600wMH bulb will veg them all for a fair amount of weeks.