Officially, USPS wants you to use that label as close to the Ship Date as possible.
Generally, you can still use a label a few days after the Ship Date, but it is solely up to the discretion of the USPS worker/branch location.
If you need to postdate a shipment to be sent at a later date, you can select a ship date for up to 30 days for USPS shipments.
If you created a label with an earlier ship date that you were unable to send, we would recommend voiding the label to prevent any delay or rejection of your shipment and using the “Edit & Reship” feature to create a new label with the correct ship date.
Shipping labels older than 90 days cannot be reprinted.
Note: XPS will not take responsibility for any rejected packages due to dating issues on the label.
Additional Help Center articles you may want to review: