I'll coment on this because I was in your shoes not too long ago. I'll try to keep it short but I tend to ramble.
My kids' pedi (he is actually a family dr specializing in kids) has two very young sons himself (so he has been here recently, and his wife is a dr too), is very good at what he does yet very practical, and HE told me that some kids can handle cows milk at 6 mos. and some not until 1 year due to their digestive tract's idividual maturity and THAT is the reason that 1 yr is recommended by all the books and pediatric guidlines (better safe than sorry in their minds and writtings). He (the dr) started his kids very slowly on cows milk around 8 or 9 mos. and said we could do the same if we wish. Now, he did stress that if food allergies, esp. milk or those related to milk, are in your family, to wait until AT LEAST 1 year; otherwise you can start slow at 8-10 mos. He also said that cows milk is not really neccesary though except for the kind of fat in it for brain development, which can be found in other sources. Calcuim is rich elsewhere. He said "Look at the biggest boned animals on earth: do they drink milk beyond suckling? Humans are the only mammals that drink other mammal's milk."
My DD, now 3.5 yrs, handled it great around 9-10 mos. My son had a milk allergy and is 21 mos and still on goat's milk. I never suspected or even thought about milk allergy in our family (even though the dr said to but the allergy is on my hubby's side) until I just knew by gut feeling that my son did not do as well on reg (milk based) formula (he was primarily nursed but suplemented formula) as soy. Don't ask me how I knew: I just did. Even my allergist, who tested my son, said "Nah....doubt it" but tested son anyways and my allergist walked back in room saying "how did you know?" All I can say is mommy gut feeling!
So, what I got out of all of this: I know all guides say wait until 12 mos but they are probably covering their buts a bit: some kids can handle it before then and some can't and some never will. If no milk allergy runs on EITHER side of the family (and ask because you may not know if they had it as babies), you can start slowly around 8-10 mos and see how the child does. If there is milk allergy in the family, maybe wait until 1 yr+ (most babies outgrow it by age 2-4). But don't stress milk as the only source (or even one of few) for brain development and calcium. The pedi also liked rice milk. Any way around it, when you do start cows milk, be SLOW and WATCH vidually. If at any time, whether you start at 8 mos or 2+ years, there is any gut feeling or clues from baby that there is an issue, back off. And know that they don't have to drink straight milk all the time and every day to be healthy!
I am going to have my son re-tested for milk allergy soon. Allergist said most babies grow out of it by age 2 (that is exactly what happened previously in hubby's family, thus the reason I did not know there was ever an issue there and thus the reason I will re-test soon as milk is in everything!!!!) but statistics say they will most likely grow out of the allergy even more so by 4. Those allergic beyond age 4 prob. always will be (fingers crossed for son)!
GOOD LUCK! Hope I helped!