You'll need A LOT of chickens to get 20 chicks a day.
chicks will hatch from artificially incubated eggs at around 21 days after hatching. If you let the mother incubate, you will end up with a lot less chickens, as she will not start incubating until all the fertilized eggs are laid, and she will not lay any more eggs until they've hatched (or so I've been told, I've never bred chickens). Also, incubating the eggs yourself ensures that you won't lose eggs to egg-breaking chickens or bad conditions.
Depending on the breed, you can expect anywhere from an egg a day to an egg every three days.
The general rule is one rooster per fifteen hens.
With this information, I'd say you would be well off to have a really good incubator, about 40 hens and for good measure, 4 roosters.
Of course, you'll need to keep some of the chicks to be replacements for the flock.
Starting out, you'll probably want to see about buying young adult chickens that have just started laying, because it can be a pain to wait until they start producing eggs.
I love chickens, but I spent a lot of money on just a flock of four. I couldn't imagine the costs of a flock of 44 (with housing, feeding, supplies, vaccinations and medications, etc)and feeding/raising the chicks until they were the size you wanted.
Of course, you can buy frozen chicks like I do. I get 25 for around $6 at Rodentpro (I think...).
Good luck if this is what you decide you want to do!

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~Sara~
5 ball pythons
1.0 Black-lined plated lizard (Lizzy Butt)
0.1 Burmese Python (Pixil)
lots of Rats
1.1 Dogs (Ozzie and Mandy)
0.1 Cat (Isis)
0.0.1 Synodontis Catfish (Big Spotty Fish)
0.1 Convict Cichlid
0.0.1 blood parrot cichlid
0.0.1 African Featherfin Catfish