Answered by RoaringMice
Some professors will have a website that right now lists what books you need. Others won't. Some schools keep lists of what books are required for which class at the campus bookstore (you can call and ask.) In general, all will give you the list of books on the first day of class (and may already assign homework for the following class), so most students tend to buy their books on that first day of class. However, some professors want you to have purchased the books before classes start, and have them on that first day. Some professors even assign reading to be done prior to that first day! So call the bookstore, and see if they keep a list of which books for which class. If they have this sort of list, go to the bookstore today, or tomorrow if they are open, and try to buy them in advance. If they don't have a list, then wait until after class on Monday to pick them up, but be prepared for some lines.