Sellers can edit the “ship by” date once, as long as the original "ship by" date hasn't passed yet, and as long as they have first obtained their buyer’s consent.
The updated date can’t be more than three weeks later than the original “ship by” date.
Go to Shop Manager > Orders & Shipping, find your transaction, and click Update next to the scheduled "ship by" date.
A window will appear where you can specify the updated "ship by" date. Include a note to your buyer letting them know why this change is happening.
After you save and send the message, the rescheduled "ship by" date will appear on your sold order and receipt pages.