How come haven't got recon yet?

I just got I new Xbox live account today (brother gets to keep the old one) and I went to go play Halo 3, and I don’t have recon. I’m only a recruit (I haven’t completed any campaign missions yet) and I don’t have recon. Do I just have to wait more for my account to recognize that I should have recon? Or? Thanks a lot.
(I know that everybody should have recon)