A 6qt container is rather small I'd double or even triple that....you don't want the worms to be over crowded as then they are more likely to munch on each other. Make sure to keep them well fed and
hydrated by feeding them leftover veggies this will help keep from them being canibalistic.
If you had two of the 6qt containers maybe...but I think you'd be better off with one
of this size for storing 500 in.
(Note...old pic and not enough substrate...needs to be about 3 or 4 inches deep. )
The larva stage begins when they are microscopic...by the time we purchase them as feeders they are already about 3 to 4 months old. The larva can under proper care and conditions live close to a year in this stage. However full grown is about 2 to 2-1/4 inches so once they reach this big they are capable of morphing when separated.