Larry,

I was taught the "Lights, Camera, Action" reminder phrase where
'camera' signifies transponder on. This mantra is to be uttered in
the beginning of the takeoff roll.

Lights: strobe, landing lights, etc.
Camera: transponder
Action: mixture, props, throttle, airspeed alive, ...

My suggestion would be strobes, landing light, transponder before taxiing
onto the runway - you do want to be very visible on the runway too. Also
get the mixture and props. The only items when are the runway are throttle
and airspeed alive - also look for other aircraft etc, think about abort
procedures, how your take off roll is progressing (I have a good story on
this one) etc... I don't like to be fiddling with stuff during the takeoff
roll because there is so much other important stuff to do and to think
about, also, when you fly complex aircraft... Well there's this pesky
little lever that also finds its way into the FAA accident reports.

The same goes for landing but in reverse; i.e. don't touch anything until
stopped on a taxiway (or something similar) - basically not on the runway.

Just my opinion.

Hilton