When did Cage replace Garcia in NRPS?

[Jim Powell]

 There's an interview tape from a Minneapolis radio station 10/19/71 where
Jerry talks about playing pedal steel for NRPS as if it's an ongoing thing,
but that tour turned out to be his last.  His last show as NRPS pedal steel
player was probably Columbus 10/31/71.  He probably didn't play for them at
Harding Theater 11/6&7/71 so maybe these were Cage's first shows?