event transition event

I have an event with 3 looping sounds controlled by an event parameter. When I change the parameter, I need to know the exact time when the event transitions from one sound to another so I can synchronize it with visual changes in my game. There’s no callback for the event that I can see and retrieving the parameter value immediately after setting it with the new value returns the new value.

Is it even possible? Using timeline position?

Thanks
-s