Getting married abroad on August 21st, job begins on August 23rd. What do I do?
The best way to handle a situation like this is to get in touch with your Head of Department / Director of Teaching in advance (perhaps, after you receive a formal offer) and discuss your situation. Make them aware of your wedding date (congratulations, btw!) and explain that you can arrive to your post right in time for your first class, but you would be grateful if your first lecture can be rescheduled to give you a bit more time. In many Universities it is customary for colleagues to step in for each other in case of sick leave or important family events (like wedding). It is much better to arrange a replacement / rescheduling in advance, rather than risk not showing (or showing not prepared) for your first class.