First, unless you will never return home, you might not need to bring everything that you ever owned to you dorm room. Most likely the room will be crowded regardless. For the first couple of months, Austin is warm and until Thanksgiving, the fifth sweater will probably be unnecessary. In terms of actual supplies, some pens, some pencils and scratch paper is usually enough. Don't worry if you don't have a computer because they are available in the computer labs in the UGL, some of the dorms, and various departments around campus.
Printers are also available.
For example, a fan might be useful if you like to sleep in a very cold room. With regards to buying books for classes, it's best to get them as soon as possible. Used copies are cheaper than new ones, but there's limited amounts and they go fast. Additionally, you can buy used books directly from other students using the official online service at TexBooks . When buying, you might also want to ask fellow Dean's Scholars if they had those classes and might have kept their books.