yes, wait for the 12/12 after transplant. approx two weeks. you dont want to throw your plant into flower after stressing it from a transplant. subcools strains also yield much better with a little increased veg time.
Soil is easier to understand, much easier. Mix, feed with water. Only supplement feed if you see plants have see visible nutrient deficiencies or know you plant well.
Also, see subcools section on Super Soil. It answers all your questions in there. and pretty much any future super soil question you have.
but really, mix, let it 'cook', water, harvest fantastic buds.