Setting the "Published" date (a list column in List 'Post') to some time/date in the future seems to have no effect on delaying the post. I'm finding it becomes publicly viewable immediately. I tried enabling the publishing feature too but that had no effect. Has anyone experienced this and might have a workaround?
You might end up in implementing a Workflow/Timer job if you want to automate the publishing process. However, you could use major/minor versioning to write "draft" versions of a post that not gets published until you click on Publish as Major Version.