I was having major trouble with this also and got rid of the game. I bought a Hori turbo controler about a month or so ago and decided to give it another go. I got it on the first attempt.
Just set the turbo controler up for the button that came up on the screen to top speed and away it went. There was no chance for the button on screen to change, the opponent was on the floor before it changed.
I hope this helps you all out.