Little seedlings need water and light thats basically it. I would hold off on nuterients for about 2 weeks then start them 1/4 strenght. If the lower "true" (spikey leaves) leaves start to turn yellow then you can give it more... Becareful not to overwater... just water it when it dry. Make sure the light is strong enough or your plant will stretch and fall over... Make sure it has a 40w+ CFL and some air movement so it will grow thick and compact.