Provide post status option for admins, change 'publish' to 'approve' 

This should allow admins to select a post status when publishing, including inheriting the source post's status, and setting a publish date if scheduling. (Also, since it uses strtotime, you should be able to schedule a post for "tomorrow", "next Thursday", etc.) I also changed the language throughout from "published" to "approved," since metadrafts may be "published" to draft status.

I've tried out basic scenarios locally but more testing would probably be prudent, especially in the context of the theme.