DrDaisy,
Don't worry. Every 1st first year will be assigned a "big brother" or "big sister" during orientation. You will get an orientation packet that will include the list of required and recommended books. However, DO NOT BUY ANY TEXTBOOKS RIGHT NOW. Many students have different styles in the way they study. I tended to use some textbooks and mostly review books along with the notes (some are bad and some are excellent) to try and learn things thoroughly. Others never touched a textbook and have done very well without one.
FYI, anatomy was the only course where I used nearly every single textbook recommended or required. The atlases that I used were Clemente, Netter, Yokouchi (the color atlas showing photographed cadavers), and Grant's dissection atlas. I really liked the Moore textbook (Baby Moore wasn't out yet when I started at NYCOM). Anatomy will be a challenging course because it is one subject that you have to unfortunately rote memorize many facts. Also, it is time consuming. One of the very few differences in our osteo education, in contrast to MD education, is that we really need to know our anatomy better because it helps you learn OMM and musculoskeletal. Eventually, the clinical anatomy will be important than the general anatomy as you continue your career.
In the meanwhile, enjoy your summer!