For intermediate results script should be able to use standard notifications. A URL can be private between application and script. Time of day seems appropriate here. Problem is we're not defining language and capabilities so its hard to describe what is in the support structure. Startup mechanisms can be entirely independent of scripts or one another.
Scripts can emulate other mechanisms such as by running periodically.
Script MIB purpose is to download and start scripts and get results. It seems easy to do a MIB to implement controls on when to run, once or periodically, elapsed or absolute time. The mechanism should be the same for all scripts. Pick the simple cases and cover them. It's good to have a central place to say what will run.