You're a little early with adding corals, not that it can't be done anyway. Just leave the lights on for the sake of the coral, it's not going to make or break anything with regard to the cycle. One way or another you're gonna get the nasties that come with a maturing tank.
The live rock came with the coral attached and someone gave me a small piece of theirs. I’ve been keeping the lights on but haven’t noticed any brown spots or the start of the giggly phase.