It perhaps wouldn’t be too difficult to add something like that, but before I even think about that, what application do you have in mind for this? I’d hate to implement something and then find out it wasn’t what you needed. For example, what if an auxiliary database failed to load? Do you not want the trigger to happen? Or maybe you want the trigger to happen whenever Panorama has finished trying to load aux databases, whether successful or failed. Then you could check for failure and act accordingly.
Also, I wonder if what you are imagining would be a feature that didn’t “trigger” until all auxiliary databases were loaded and synchronized. That would be a lot more difficult.
You could do all of this now with a timer, for example check once per second until everything is opened. The timer could be instantiated by the .Initialize code. But I think whether that is a good solution or not depends on what you have in mind.