Comment by RichardCA

It's debatable whether it was first recorded in '63 or '64.

The genesis of Guaraldi's involvement was a 1963 documentary "A Boy Named Charlie Brown" which has nothing to do with the 1969 animated feature.

This was produced for TV but never aired, and recently surfaced on Youtube: https://youtu.be/UGAs5fZUvBM&t=425s

To complicate things further, Guaraldi released "Jazz Impressions of A Boy Named Charlie Brown" (once again, based on the 1963 documentary) but these recordings are not the same as the cues used in the documentary.