I think Super Start is hard, too.

Super Start just works by pressing the button within maybe 2 or 3 frames. There is no problem if you press the button at other times: keeping the rhythm, or mashing. As an example, I press the button twice with left and right thumbs, with slightly different timing.

Besides, the countdown sound is different for each course, so it might be better to watch the signal.

To be honest, I don't know a certain way so far. But I hope this helps you.

Sorry for bad English