How do you know you're in a small pool? There's only 1 or 2 schools that I know of that explicitly tell you you're in a smaller pool of applicants to be considered for an interview. Usually its just an ii, a hold, or silence. If you had applied earlier, you would be competing against fewer people for interview spots, so it's possible, even probable that you're right, assuming you have a good app. I think everyone on here would tell you that the easiest thing you can do to help yourself is to apply early.