You could leave this step to the next day if you wish to publish your content at a certain time and day. All you have to do is to log into Github at the time you wish to publish and go through the steps below
Step 1. Go to the pull request that has been approved (you can follow the same steps by going to Pull request tab, and select the correct pull request in the list)
Step 2. Scroll to the bottom of the page and you'll see the green button that says, Merge Pull Request and click on it.
Step 3. You will be prompted another button to Confirm Merge. Click on it, and voila! Your site is live now!
Once you've merged the pull request, your changes will be reflected on your live site.
If your site is not launched yet, proceed to the next page to find out what to do next.