I wouldnt recommended using 18-4-12 for another week or maybe even two.

It has a huge nitrogen dosage + a phosophorus dosage, I think it may over nute the plants. If they start to droop, give them a alittle bit of it with next watering, cant help to try something new? Hell who knows you could even get a mad growth spirt out of it. Good luck

Might I recommend buying Bat guana from the net.