In the Player controls, tap on the Mixer button (second one from the right at the bottom of the screen) to change the Count-in settings.
Select zero for No count-in or set the volume of the count in with the slider.
You can also change the click sounds.
The Auto setting will automatically play one or two measures - depending on the tempo allowing more time for faster tempos before it starts playing.
In case you can't see the count-in when you open the mixer, scroll down to reveal it.