Depends on temperature...but in a couple of days the eggs will disappear...and there will be a pile of wigglers somewhere in the tank...they'll be free swimming a couple of/three days later...that's when you want to feed them.
Some people swear by newly hatched brine but I have great luck with super fine flake like Golden Pearls...
Good luck - I have I think 2m/1f firemouths in my 125 that want to spawn but can't control their territory enough...
Matt