If we are counting for family, church and school, I can't remember a time when I didn't sing for others. I don't know if they do it any more but, at the time I grew up in Wales, once a year most schools had a school eisteddfod, where everyone was expected to participate. The participation might not be exactly musical, it might be choral speaking ( a sort of group recitation ) or providing sound effects but everyone had to do something. Going on stage didn't seem like such a big deal since everyone did it. I was also in school choirs and choral groups, almost from the day I first went to school. Since we kept going to perform for local old people's homes etc it meant every now and then we had a legit reason to miss lessons! But the first time I sang in a folk club would have been in the New Inn on Tottenham Court Road some 20 years ago. I think I sang All Around My Hat (a song which I still sing).