As soon as they're out of the wriggler stage (can last 2-3 days, where fry use up their yolk sack for food), and start free swimming you should start feeding, not before.
I usually start with newly hatched artemia (brine shrimp)for first food, I buy the eggs which hatch in 24 to 48 hours.
Small frequent feedings throughout the day, are better than just a couple large ones, this regime works for all cichlids, not only festae.
As the fry grow a day or 2, I puree regular pellets, deshelled peas, or flake food in tank water and inject it into the school of fry with a turkey baster or pipette. There are also commercial fry foods available.
As the fry grow you will want to have a number of small tanks ready for grow out, where you separate large from small fry, otherwise the large ones kill the small ones. And by separating them in different tanks, it helps them all grow faster, these small tanks need lots of water changes to keep from fouling, with all the waste the fry produce. The water changes promote growth, and keep environmental defects from occurring.
