If you want to set the date of an entry to something other than the present, you can use the schedule feature in WordPress.
Locate the Publish date setting for the entry at the top of the Document tab. Click the date or “Immediately” label to reveal a date picker. Choose the date that you want for the entry. Select a date in the past to backdate the entry, or choose a future date to schedule it to publish automatically on that date.
If you are using the Classic Editor, the controls are different but work similarly.
Once you have selected the date, save the change by clicking the Update button. If you selected a date in the future, the Publish button changes to Schedule. Click Schedule to save the entry.
If your entry has been scheduled for a future date, it will not appear on your site until the scheduled date and time. This is a great feature to have content automatically published to your site while you are away.