You bring your whitecoat with you to the ceremony, carry it up to the stage with you, and then hand it to whoever puts it on you. When you order it with their order form, you have to pick it up yourself at the bookstore and take it with you to the ceremony. Super easy (once someone tells you how it works 🙂)
If any of you guys have any questions that you think should be obvious, but you don't know the answer, really do ask. My 2nd year buddy (who is a 4th year now! holy cow!) said a lot of people in her class didn't even know where to go the first day. Her class, and moving on down have tried to make sure everything is out there, but really, the school isn't always good about telling you things so just ask! 🙂