For the record, generally you wouldn't want to
feed chicken-fed maggots back to chickens because a maggot isn't
enough of a gap to prevent passing diseases. So I'd be looking for other critters to use as your growing medium - like road-kill, surplus racoon, any surplus rodents (
mice, rats, squirrel,
rabbits etc).
Where I live we've got both a feral rabbit problem and an invasive squirrel problem, and I'm really thinking that a maggot bucket might be very useful. Your questions about time span are of great interest to me.
It sounds like the link John C Daley quoted but didn't include, would give some good information about using manure as a feed-stock. Covering animal material with manure, might help control the smell, as that could become an issue if using dead animals - they do give off a unique smell!
I bury my
chicken offal where the chickens won't get it and get the worms to turn it into useful soil. I have read about it being put in buckets over a
pond to feed fish. Chicken - maggot - fish food is a safe gap disease wise, and theoretically, you could feed the fish back to the chickens with or without a maggot phase, but not too often or the eggs and meat of the chicken could start tasting fishy.