At 68 degrees Fahrenheit (20 degrees Celsius), which is considered to be the best incubation temperature, the eggs hatch in about 3 days. I kept the water about 3 to 4 inches deep in the fry tanks, with plenty of aeration and sponge filters. The fry essentially hang on things for several days while they digest the remainder of the egg. When they become free swimming they need to be fed.
Above: The fry the first day after hatching. These fish are "adhered" to the tank glass. They can only swim very short distances.
Goldfish fry are quite large for egg layers. I raised some Paradise Fish a few years ago and it was weeks before their fry were as large as newly hatched goldfish. What this means is that goldfish can be started out almost as if they were live bearer fry. I used a little strained egg yolk, but introduced newly hatched brine shrimp almost immediately. Most of the fry seemed to be able to handle the brine shrimp.
Two important notes:
I made my own brine shrimp nets to collect nauplii (another trip to the fabric store ) and used the material for straining the egg yolk. The ideal would be to have food in front of the fry constantly. My best approximation was to feed 4 times per day. People with sources of the fresh water crustacean daphnia are able to keep a continuous food supply in front of the fish and get phenomenal growth rates as a result. But even just using sifted flake food you can raise goldfish to maturity.
Above: Fed on brine shrimp, the fry at 2 weeks are recognizable as little goldfish with early back and tail characteristics becoming visible. For reference, the scale in this picture is 0.5X that of the previous fry picture.