Yes, 1965 in Wellington NZ. And I've been to most of the other Wellington/National Folk Festivals since then - only missed 1972 and 1990. Both times I was in Britain and we went to other folk festivals instead.
Some NFFs were in High Schools or the University but we outgrew the venues. It was held in the middle of our winter, (beginning of June) and folkies from outside Wellington had to be billeted.
Now it's a camping festival, held as summer is beginning, (end of October) with a huge marquee and lots of tents but also bunk houses for the people like me who no longer wish to sleep on the ground. Been there, done that, not any more thank you!
Robyn