By “lose [your] work” I’m guessing you’re asking if the credits you get your first quarter would still count towards anything? The answer to that is yes, especially if you plan well. Your first quarter is spent taking one or two (somestimes three, depending on major) prereqs, and one or two GEs. If you do something like chemistry and calculus as prereqs your first quarter, those apply to so many majors that you wouldn’t be behind at all. Even if something didn’t apply directly to your new major, they can always apply either as GE credits or just as credits towards graduation.
To summarize: Anything you take at this point in college counts towards something.
If you do get in off the waitlist, you’ll have a chance to discuss all of this one-on-one with an adviser at orientation. When you get to orientation, just explain that you want to switch majors. Orientation leaders are trained to be able to advise for all majors, so they’ll be able to help you out. It’s more common than you may realize.