Timestamps

WordPress will also let you alter the timestamp of your post. This is useful if you are writing a post today that you wish you'd published yesterday, or if you're writing a post in advance and don't want it to show up until the right day. By default, the timestamp will be set to the present moment. To change it, just find the Publish box, and click on the Edit link (next to the calendar icon and Publish immediately). New fields will show up, and you will be able to alter the publication date:

Change the details, click on the OK button, and then click on Publish or Schedule (depending on whether your new publication date is set in the past or in the future).