Best advice I can give on Convict Cichlid breeding is:
DON'T
I usually try not to be so negative, and all fish have their virtues, but these guys will kill everything in your tank once they spawn, and mine even took a couple of bites out of my arm when I reached in to move a rock. You'll end up with more fry than you know what to do with, and nobody will want them. There are a lot of fish that are very similar to the convict in a lot of ways (including ease of breeding) and most of them will be much easier to find homes for. Really, I know many people who have bred convicts, including myself, and pretty much every one of them regrets it on some level. I'm not telling you what to do with your tanks, that's your decision, but be prepared for a hassle, and definitely don't put anything else in that tank, half the time the parents are so defensive that they'll kill each other to protect the babies.