Asynchronous Plugin in RTC

I'm not sure if there is a mechanism to trigger a server side Task to run at a given time.

You could write your own instance of AbstractAutoScheduledTask and have it run every couple of minutes (you would still want to it run every couple of minutes vs couple of seconds to reduce the server load), and then in your implementation you simply check the time at the start, and return if it's not at 12:00 +/- your sleep time. So if it's scheduled to run every 3 min, then at least you'll be +/- 3 min away from 12:00 (so hopefully that is good enough)