So, we don't provide any ability to 'introspect' the bindings and know that they're in progress. What you can do instead of bindings is issue your named query from scripting; you'll want to wire up the appropriate propertyChange scripting events to fire your script, but if you do that then you'll be able to set some 'loading' flag (and react to that in your UI accordingly) and then, in a background thread, execute your named query (and then jump back to the EDT to deliver the results).
It's an immediate, significant jump in complexity, unfortunately, but is the best way to get what you want.
@pturmel wrote a scripting module, later.py, that helps a lot with the 'boilerplate' around running an async task and returning results on the main thread: