yes, for sure burn. You shouldn't give any ferts to seedlings untill they have 4 sets of true leafs.

also, I seed in a "soiless mix". because seedlings dont need or want any nutes. I have a mix of sand, perlite and peatmoss. Works great.

I plant them in very small pots 2inch by 2 inch (peat pots) once the'e got 4 sets of leafs i pop the pot into good soil after a few days the roots grow into the good soil and the take off.