You don't have to wait to make a refund in your store, a refund can be issued as soon as it is needed to be done.
To issue refund from PayPal:
If your store order was payed via paypal, than login to your paypal account, find the order in question and click "details", and than "issue a refund".
Issue refund from your store:
If your store order was payed via credit cart, navigate to SETTINGS -> ORDERS and find the order in question, and click the quantity sign on the product image to refund 1 item (partial refund).
Please reply if you have any other questions about issuing refunds.
Steve - eez.io support