After seeing this Auto launch countdown, I liked the idea of having ten seconds to put your Tx on the ground, pick up the plane and then wait for the motor to spin, before launching.
It seems that CONDITION_DELAY function works in FLIGHT PLAN menu in APM Planner in the COMMAND column.
This way one can first delay the first command from happening (for instance TAKEOFF) and add the corresponding countdown sound in FrSky Taranis. 10 Second Countdown.wav
I intend to try this out next week, once done, I will post the results here, if you can't wait, try it out for yourselves!