When my DS7 was in pre-K, he whizzed through the pre-k, k, 1st grade curriculum within 2 1/2 months. Then the headmaster refused to advance him into the 2nd/3rd grade class or accommodate him. He said that socially/emotionally DS wouldn't fit in since he has a late birthday and had just turned 5. I understood, but was frustrated at the same time.
Since it was a private school, we didn't have much to fall back on so we enrolled him at another school for the remainder of pre-k and for kindergarten last year. I'm now homeschooling him and can work at his pace/level.
If the school or district is willing to work with you, then perhaps you can get somewhere. However, I'd say that there are so many variables at play with these kids that it can be difficult with school, depending on the child, teacher, school, other kids, curriculum, etc. Try to work with the school/teacher and see what happens.
