Don use the stop mode in metronome settings, if you haven't started play the metronome still quides you so when you do hit start you are in the ballpark. That's assuming your MP3 has an immediate start, which all of mine do for that reason , I can play around live before start knowing when I hit start I am in time this includes using any loops , I can play live all the way to any loop start point and enter the backing track in any part of a song having the viual metronome keeping me in time so it smoothly comes in. Otherwise pre program your audio file to give you what you want.