I used to feed mine Country Lane chick starter from start to finish. Get at my local Orscheln's. More recently I have been feeding them that for about 4 weeks and then switching to an 18% all flock feed. I know some feed a higher protein to get them bigger faster. I like a little slower growth - seems to add more meat and less fat. I butcher mine almost exclusively for roasters instead of fryers...so they are 10 weeks or more when I process.
I always fed mine turkey feed, as in turkey starter, turkey grower, and turkey finisher. Where I lived, I couldn't get broiler feed. The turkey feed worked out great.
18% layer mash and at 4 weeks I start adding whole corn. By eight weeks they are at 50% corn and stay at that until ten weeks. I dress them myself and they are just beautiful .Wt of about 7 lbs. Much cheaper feeding this way. Never have any loses.
I start mine on gamebird feed. I start everything on gamebird feed around here, because it's generally 28% protein, and encourages good growth. After 4 weeks with the meat birds I go down to 24%, and finish off with 20% plus all the bugs and grass they care to consume. I will be tractoring them again this year.