Out of the 3 cockerels I have I'm going to choose the largest one. He's huge compared to the other 2. Should I just keep going on that vein? I know they'll probably never be up to show quality. I'm looking for size wise. I read online that if you keep choosing the largest ones to breed in 4 generations you should have the right size chickens since hatchery stock is smaller.
I've got my doubts that 4 generations from hatchery stock will get you anywhere near the size breeders have been working on since, (or before) Brahmas were included in the first American Standard of Perfection in 1874.
I've gotten to feeling pretty good about the size of some of the birds in my various Brahma projects over the years, until I get to a large show and stand next to a row of top flight large fowl lights. Talk about a reality check.
As ocap and others have mentioned throughout these threads, you would be light years, and money, ahead in the long run by attaining quality stock from a top breeder.
I might advise you to work with what you have for the time being, to work out the bugs, learn some of the finer points of raising, breeding, hatching, managing a healthy flock while you cultivate some contacts and relationships with breeders, and save up for taking the next step. I know I have sold birds to people who would call back in a couple months wanting to know if I had any more I might part with. They really liked them, but had no idea a coon could squeeze through such a small space, or could tear through chicken wire, or so on. All things a person should learn with their practice birds before laying out the cash for good breeding stock.