textbooks

Hey everyone! I have a question about textbooks. Should I buy them before I get to campus or wait until the course starts. One of my classes says I should wait (Chemistry 1610) but that I need to get the lab manual. I also am pretty sure I need a textbook for 1151 but it isn't listed in the textbooks I need to purchase. Does anyone have any experience with this? What should this process look like. Thanks :)