To what extent did Brian write down music/chords while composing?

[Pet Sounder]

Sorry if this is has been addressed before.  Tried the search feature and couldn't find an answer to this one.  For instance, did he get from the sandbox piano the night he wrote Surf's Up with the chords written down?  Or did he keep it in his head until he recorded a piano demo?  I know at times he would pass out chord sheets to the wrecking crew.  Not sure if he scribbled those down before the session or had some sort of original copy he'd write himself the moment he composed the song.