Well we can clear it up a bit, surely, was it June '68 or 1970... is Danny on there? He joined in August '68, so if he's on there (I don't have the tape), then it's later than that. If he's not present, then it must be June '68.
Also, I recall Dinky Dawson saying in his book that Janis Joplin ambushed Danny and taught him a thing or two... I don't have the book here, but Dawson mentioned her a few times as being present at gigs in certain towns, and she made a point of making a conquest of Danny. Might that have been 1970?