Publish posts but have them hidden until scheduled time

I’m looking to be able to publish posts so that they are only visible if you know the URL but have them hidden from everywhere (RSS feed, etc..) until a scheduled time when the post becomes visible to everybody.

I’m trying to do this for a number of reasons, including advertisers seeing sponsored posts before they go up, and third party services who’s scheduled posts features don’t display properly unless they can scrape the meta data from the post.

This Plugin “WP Hide Post” can achieve the hiding part, but not the “un-hiding on schedule” but hasn’t been updates in 2 years and the authors own website is gone defunct as well.

Any suggestions would be greatly appreciated ??