Schedule Based on Precise Date/Time Rather than Recurring Schedule

I am planning to start setting up a cross promo venture, which (ideally) would involve each author posting their story at the exact same time so readers can hop from story to story without issue. I also don’t want to expect every author to participate every time because I know some write slower/don’t have time or maybe have conflicts on specific weeks.

It would be nice to offer an option to specify a date/time instead of a recurring schedule, which would make coordinating cross promo with other authors a bit easier.