The WordPress Page Scheduling feature is found in the Publish box in the upper right corner of the page admin panel.
*NOTE – be sure your timezone is setup correctly in Settings -> General. Check this article for more info.
To schedule a page for publication, click the Edit link next to Publish Immediately. You will now see a drop-down with options to select the month, day and year to publish the page. You can even select the exact hour and minute to publish.
For example, if you’d like to publish this page at 8 a.m. tomorrow, select tomorrow’s date, set the time for 8 a.m., and click Ok. You’ll now see the Schedule button has appeared.
Click the Schedule button and you’ll see the status of this page has changed to scheduled with details for the exact date and time it will be published.
If you change your mind and want to publish this page immediately, click the Edit link next to the scheduled publish time. Just update the time to today’s date and the current time and this will immediately publish the page.