This plugin doesn't actually hold posts to be published. it just pre-dates them to 1970 until the proper time has elapsed. Then the post is re-dated. Unfortunately this means posts that should be invisible still show up on random post widgets, and via searches. It also plays havoc with permalinks if you use date tags.
I was really hoping to find a way to pre-post without having to figure out how many days ahead my posts are, but this just isn't going to do it. I'd love to just publish away, and have my posts automatically appear with a 20 hour gap between all posts.