Andrew Sarangan wrote:

In fact I would recommend to turn the transponder on before even getting
on the runway.

Same here. I'll run through the "lights, camera, action" checklist as I
start the taxi roll over the hold short line. I've never had to wait more
than a minute or so between a "position and hold" and "takeoff", so it's
never been a problem. The only "non-flying" thing I do when starting the
actual t/o roll is to start the timer, and I do that before the throttle.

I don't want my hand to be near the transponder or strobe switch when I
decide to abort a t/o.

- Andrew