You should be fine. Are you using the "hassle free return" system through eBay? If so, eBay usually gives you up to 7 days from when the item shows return delivered, for you to make the refund. If the packages are shown "delivered" the Monday after you leave, you should (call eBay, double check) have till the following Monday to initial the return. And any day after that works in your favor as it will extend the refund deadline.
7/6/14 at 1:26pm