It is important to note that once a credit or an invoice are issued, the date cannot be changed. The following are the steps to correct a credit with an incorrect date (please note that to correct an incorrect invoice date, the sign on the quantities must be inverse):
Step 1: Create a Sales Order with a Misc. Item with a price equal to the credit amount, a cost of $0, and a quantity of 1
Step 2: Ship the Sales Order with the same bad date
Step 3: Apply the bad credit to the Sales Order
Step 4: Create a second Sales Order with a quantity of -1 and the correct credit amount, and ship with the correct date.
If there are any costs associated with the erroneous credit, they should be moved with journal entries.