I’m working on an interface at the moment that allows both once-on events happening at a specific moment, as well as an event at the start and one at the end with a specific payload. It’s using
node-red-contrib-cron-plus for the scheduling and
node-red-contrib-uibuilder for the interface on the inside. It’s a slow process as I’m still learning to work with this component library but I’m pleasantly surprised with the results so far. The interface is similar to the Microsoft Outlook builtin calendar/scheduler, so easy on usability.
A lot of work to create, but yes it is possible.