Everyone plans for what "everyday life" will cost during college but few think about the expenses they'll incur leading up to that steady state. I just ate into more than half of my summer earnings before spending one night in my new place.
You can get ahead of this. Start by imagining your parents' house and then think about how much it costed to get the place looking exactly the way it is. When moving into a new apartment, you're about to go through the same thing.
Furnishing an apartment can be a serious investment, so start making a list of the things you can take from home or ask your roommates to contribute. Then, be economical about how you're going to get those things into the new place. Movers are expensive, but so is buying a brand new mattress and bed frame on-campus during peak move-in season.