You can't refuse to make other plans hoping that you'll hear back from the school that waitlisted you. Depending on the college and the year (even if you look up their statistics from last year, they may be wildly different this year), your chances of hearing good news later are either slim, very slim, or maddeningly slim. You have to move on.
Somewhere in your mind, though, you'll keep wondering what to do if it turns out you actually are one of the rare few who gets a spot later. Let's go over two different approaches to dealing with that possibility so it doesn't add anxiety to all your days between now and September.