I wouldn't give bread to growing meat birds. That will decrease the protein and vitamins in their feed over all and those birds desperately need the protein in order to grow legs strong enough to hold up their bodies. They are very prone to slipped tendons and leg problems starting at about 5-6 weeks old. I figure about 10 lbs of feed per meat bird for 8 weeks. If you plan on butchering yourself, do the boys at 6 weeks and the girls at 7 weeks to spread out the work. I at most do 10 birds in a day because I have to do it myself. Raise them on a high protein starter ration that only contains amprolium so you don't have to worry about withdrawal times.
I say skip that fry pan special. I raise leghorns for eggs, and 5 month old roosters of the leghorn type dress out at 2.5-3 lbs. Not worth the feed and time for those flighty skin and bones.