When were checkerboard fiducial markers first used in aircraft development?
This was not already established practice in 1942.  Not even in the early 1950's NACA crash tests, which were so methodical that you'd have expected these checkerboards:  seven movie cameras along the runway, a flashing light atop the fuselage for movie synchronization, a pile of onboard cameras and instruments, white paint and red-dyed fuel for better imaging.  The closest this came to checkerboards was dotted lines on the fuselage sides.

This long NASA video includes many images of these aircraft.  No checkerboards anywhere.

A skim through online photos suggests that even automotive crash tests didn't start using checkerboard fiducials until the 1960's.