Doing some of my own on-line research here. My birthday (I can't believe I'm sharing all this stuff on-line) is April 2nd 1970, which means I would have been conceived in late June or early July of 1969. Dave Van Ronk was in Montreal on the 29th of June 1969 opening for Joni Mitchell at Salle Wilfred Pelletier. I'd say that's pretty close. I'll will post more info as I get more.

Jason,

I was at that Joni Mitchell concert. There was no opening act. I was a big Dave Van Ronk fan and had already seen him a couple of times in coffee houses, so I would definitely remember him if he'd played the concert.

I saw Joni a couple of weeks later at Tanglewood in Massachusetts and the opening acts were Tim Hardin and the Paul Butterfield Blues Band. I remember those concerts very well and recall thinking about how different it was to see her do a whole concert on her own and another when she only did 45 minutes on her own.