You can have books or magazines or paper before you are processed to take the test. This will help you pass the time if you get to the testing center hours ahead of the report time. Personally, I tore a few prep-test practice problems out and worked through them to get my mind going. I wouldn't have been able to concentrate on a book.
However, they will not let you sit for the test with scratch paper or a magazine or what have you, so you will have to throw it out before you are processed. This is why I just took a few problems. No big deal throwing them out.