for me it took about 3 days for the plant to pop out of dirt after being germinated in papertowels so you might be O.K, or maybe you could put them by a window if they do pop out before you get your light. Be sure not to put the hps too close to the seedlings or they'll fry up in no time. It's better to start farther away and then gradually go closer as you see fit.

keep the soil moist but not soaking wet until they sprout, you can put saran wrap over the pots using toothpicks to prop the wrap up to help keep moisture in and you can also see if anything sprouted.

Thats all for now