I played around with the two values you mentioned (disabling the timer when both values are 0), but that didn't work. Both values are 0 almost every time, which stops the timer immediately.

Now I'm using a second timer that is enabled in the mouseup event (when user releases mouse button) and stops the first timer after 4 seconds, so there's just enough time for the waves to fade away. Probably not the best way, but it works.