Ordering invitations, what return address when moving

When I order my invitations I may not know my new address. By the time I send them and receive rsvps I should be in my location. I'm hoping that I'll move before I need to order the invitations so this won't be an issue, but if I have to be in my current place until the lease is up, I should order the invitations before I move or else rush the order. And it's not as simple as saying to put the return address as a po box because my intentions are to move about 100 miles to a different city because I'm looking for a job in the other city. What should I do?
FYI: parents live in a whole different state and there's no wedding party either.