Pinned post is always displayed above the rest of your blog posts. You can use it to show any important or urgent information to your visitors.
How-to
It's really easy to make pinned post with Postach.io. Before publishing a post just change creation date to any future date.
Advantage of this method is that you can set the date when the post will become a regular post. The post will "automatically" unlock on the date you specified above.