I wait about 3 -5 days after they hatch and put them into the 10 gal with all the other babies. Man DO I HAVE A TON OF BABIES . There is no way I could ever count them . The whole bottom of the tank in the gravel is all cories
Good luck with yours.
Also I read somewhere that you MUST have worms or baby brine to raise baby cories. I only use First Bites and crushed tropical crisps.