Trigger song start by pressing the keyboard?

No, there is no 'start' function via keys.

Various options though:-

1. Record all or part of the intro chord into the sequencer so you can use one hand for part or let it play first chord and you pick up thereafter

2. Add a one or two bar 'empty' midi section at the start of the song to allow you to press start...and get ready for the song and visually watch for your start point.

3. Do as 2 but send a click track to the sub-out and use ear phones to hear your start point.

4. Do as 2 but use your pads on track 16 to give you a visual count down so one, two or four lights illuminate as a count down to the chord start point. You can 'record' a very very low volume sound ( virtually silence) onto the pads and set them to trigger on say beat 1, beat 2, beat 3 and beat 4. Or stagger the gas to give you a quickening lead-in.This is using the pads in their 'sample pad' mode but 'reversing' its purpose to light a pad at sett points rather than the pad playing a sound at those set points.

You can send Song Start/Stop MIDI commands with an external controller.

Another thought...record your two handed Chord to Pad 1. Then you can play it 'live' with one finger on the keyboard ie. the bottom C note on FA06.

Thanks for your answers. I'll give a try to these ideas and see which one fits me best

According to the Reference Manual you can assign foot controller 1 or 2 to song start/stop.

Regards,
RoDi