You burnt the hell out of your plant. That is very very very strong shit. I would never put something that strong on my plants. That stuff is for your yard, one bag is supposed to cover like 5,000-15,000 square feet.
The potting soil you used should already have enough nutrients in it to get you through the first 6-8 weeks.
Yeah I would gently transplant into new soil and dont feed for a few weeks. New sprouts dont need feeding for a few weeks and even at that...its pretty strong fertilizer. I would do about half to a 3rd of the dose.