Most of the community college courses should transfer to a 4 year college, meaning you'd only have 2 years left to do. You'd have to make sure that you took all of your pre-med classes, and it'd best if you took those at the 4 year college. Because of all of the pre-med requirements, it is possible it will take you more than 4 years total (2 community college + 2 at 4-year college). Hope that clears things up.