Don't use anything with NUTES!

Go get Jiffy Seedling Mix. It's available at homedespot now that they have started stocking Spring related stuff...

Wait until you get to the veg stage 5th node and move to a nute-less soil mix (I use 30% top soil/30% MG ORGANIC Mix/ 40% Perlite).

You want to be able to control the nutes through watering.