This is being discussed in the Showdown topic right now.
Rather than discuss there thought i'd start a new thread..
I personally think the start position should be a point (marker, disc, spot of paint, etc.) on the ground - not 2 feet in the air.
It makes setup easier and more consistent from range to range.
From the SCSA website:
Section 5 - 2.3
In the Rimfire Match, there will be an aiming point (flag or sign) centered downrange directly in front of each shooters box approximately 10’ away and 2’ high. Where multiple boxes are on a stage such as in Outer Limits, the flag will be placed in the center of the array. The competitor while waiting for the start signal, must be pointing/aiming their gun at the flag/sign with the finger off the trigger.