dont need lights until they pop out man. try keeping them around 80 degrees. and if you can get yourself some rockwool you will get almost 100% sucess.
I think leaving the light on is a better idea. What is the extra light going to do? Especially if it's a floro, because they cost heardly nothing to run. Right when my plant sprouted, it was greeted by the "sun" (floro light) just like it would be in nature.