Typically, the eggs will hatch out anywhere from 60-72 hours after spawning takes place. This is temperature dependent, with higher temps causing faster hatching. Keep the temp about 78-82 and you should see eggs about 2.5 days after they were laid. I don't expect any to survive in a community tank, but you can rehome them and artificially hatch them out. With the spawn being in the sand like that, I would get a large spoon or something else and dig the eggs and enough sand out to ensure that the eggs don't turn over. You can put the eggs into a 1g tank with a heater and hatch them out there. Use an airstone placed directly above the eggs to keep the water flowing so that the surface of the water gently rolls. Also add about 5 drops of hydrogen peroxide every 12 hours as an antifungal agent.