This all depends on what exactly you are talking about. The kind of soil. The size of the planter. The brand/type of nutrients. Your ability to control pH.
Honestly, I don't think it needs anything but time and moisture over the next few days/week. Wait for at least another leaf set to poke through before doing anything with food. Soil is food. Let the microbes break down the organics and feed the plant naturally. I think maybe a drop of superthrive in a gallon of water is about all you might need at the moment.