Some Phish shows featuring rotation jams are:
December 29, 1996
Corestates Spectrum, Philadelphia, PA
The rotation jam grew out of You Enjoy Myself and ultimately became Sixteen Candles (with all band members back on their normal instruments).
February 13, 1997
Shepherd's Bush Empire, London, United Kingdom
The rotation jam was, in fact, during Walfredo but this show was the first performance of Walfredo. As such, the existence of the rotation jam precedes Walfredo.