A light cycle 12/12 will trigger flowering. For vegetative growth 18 hours of light and 6 hours of absolute darkness is a fool proof way to go. Although some will go with 24 hours of light and no darkness at all, you may find a couple of cons to that ( heat, cost, etc. ). For vegetative growth, N-P-K should always be in favor of nitrogen. Get a good 20-20-20 and a 5-0-0 ( or whatever ... ) boost to it.
You should read on fertilizing, I can tell you're going to make a f*cking mess if you don't ...