brahmas are a very troubled breed. pretty much any asiatic, or english strain is i guess. i know i have a ton of work to do on my australorps. i guess too, the number of generations would depend partially on the ratio of birds from each generation. i might do it wrong, but first i look at overall shape; then i work with width, and and finally color.
this method does seem to work well for me, but im still fairly new and have much to learn. ill put it down, you tell me how you would change it:
first generation from hatchery, select no more than 2 roosters and 2 hens from 50 hatchery birds. breed 2 months worth of chicks (approx 20 from each pair) switch hens between roosters and breed 2 more months. then sell the lower quality pair. use the best pair as extra mates as needed during molts, or periods of low egg production.
second generation: cull any comb defects, eye defects, leg defects and overall type defects @ 1 month and @3 months - culling at least 1/2 of the chickens each time. so you start with approx. 75 live birds, cull 30-35 the first time around, then 15 or so the next time around. you should still have about 15-20 surviving chickens @ breeding age. cull down to your best 4 hens and 2 roosters.
third generation: follow above instructions, but i only breed for one month; since egg production is doubled.
usually by the 4th generation i have pretty good type, but with any show bird its always a work in progress.
the main problem i have seen - some of the slow growers turn out to be beautiful chickens. but they also usually seem to lay later too.