As a seller, you can set the delivery period in the AliExpress backend to manage your orders.

Here are the steps to set the delivery period:

1. Log in to the AliExpress seller backend and enter the "Transaction Management" page.

2. Click the "Settings" button and select "Logistics Service" in the drop-down menu.

3. In the "Logistics Service" page, find the logistics method for which you want to set the delivery period and click the "Edit" button.

4. In the pop-up window, find "Delivery Time" and enter the delivery period you want to set.

5. Save changes and exit the page.

Please note that the default delivery period on AliExpress is 7 days. If you fail to ship within the set delivery period, the order may be cancelled or your credit rating may be affected. Therefore, please make sure to set the delivery period reasonably based on your actual delivery capabilities and logistics service needs.