Alera, I think your idea of sending the announcement after the ceremony is a good one. It keeps the communication line open as you hope to do. I know you have worked so hard on your degree; you should be really proud of yourself! I'm so thrilled for you and I think it is really touching that your Dad will drive to be there.
I hope you will take some time to relax once all the finals are done and papers submitted. You deserve it!!