Some additional informations in The Complete Birth of the Bebop (especially 2.1).
2.1:
This is the longest known recording.
2.2:
There is some confusion about the correct title, which has been first issued as I Got Rhythm in Early Bird: Charlie Parker with Jay McShann and his Orchestra (Stash CD 542).
Indeed, during this session, three tracks were played:
1. Walkin' and Swingin' (aka Jumpin' at the Woodside) (Incomplete.) (?:??)
2. I Got Rhythm (3:37)
3. Jay McShann Blues, title unknown (?:??)
and this is supposedly #2.
It's unknown if the two other items are released or not.
Anyhow:
Date: 09 August 1940.
Place: Trocadora Ballroom, Wichita, Kansas.
Musicians: Jay McShann Orchestra: Buddy Anderson and Orville Minor trumpet, Bob Gould trombone, Charles Parker, & John Jackson alto sax, Bob Mabane tenor sax, Jay McShann piano, Gene Ramey bass, Gus Johnson drums.
Recording: Private recordings by Pete Armstrong and Fred Higgins, university students, on paper disc, using a portable recorder.