WordPress – Publish Posts But Have Them Hidden Until A Scheduled Time?

I asked this on the WordPress forums but haven’t had any luck yet, so I’m going to ask here in the hopes that one of my wonderful readers will know of a possible solutions:

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 whos scheduled posts features don’t display properly unless they can scrape the meta data from the post (I’m looking at you Facebook!).

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

Any suggestions would be greatly appreciated :)