Wearing scubs would not be unproffessional. As a traveler I go to orientation 2-4 times a year and 1/3 to 1/2 wear scrubs. If they told you it is 730-1230 you are probably done at 1230 although sometimes you meet with your manager for a few minutes for the schedule. Don't stress over it. You have worked hard to get here just enjoy your time with paperwork cause once you are on the floor you will earn your money