It should take 7-10 days if kept moist and warm at all times. Some eggs will still hatch up to a week after the fact.. Mine hatched on Dec. 14th and I STILL see little newborn crickets.
I use Organic Cactus Potting Soil and a 10 gal tank. I put the soil in the tank about 1/2 thick and let about 10 crickets go. I let them lay their eggs for about 3 days and then took the females out. The females have the long ovipositor. The inject that into the soil and let the eggs go. I also...