It's temperature dependant. They are sensitive to light. 72 hrs at 28 deg, 4-5 days at 24. The parents will eat the babies, so make sure there is no gravel on the bottom (the babies will fall down the gaps and die), put sand on the bottom, and some broken pots so the babies can hide under the gaps. Or you can scrape the eggs out, but keep a good water movement over them and add some meth blue. To make them hatch, you can shine a torch at them after 3.5 days and they'll hatch. I've had a better success rate hatching them earlier.
They keep their egg sacks for 5 days, and can only eat decaps, microworm or bbs for a few days until they get bigger. Remove any left over food, and do a water change every time you walk past and they'll grow quickly.