It was evening services for me - small affairs, which were mainly kept going for the sake of some of the Sunday School leaders who missed out on some of the sections of the morning service. Mind you, before that I'd had a year or more of morning services at the same church, gradually getting used to using the mic in front of me and building my confidence with singing and playing at the same time. Prior to that I'd led worship a handful of times but was generally just "bass player, no vox".
I suppose the common theme is a small and quite forgiving audience! ;-)
I got my start playing with a worship band circa 1971 filling in on organ in a very country music guitar and banjo type church. (I had to tune the organ to the guitars as it lost its registration every time it was turned off) I was a sophmore in high school.
I got my start leading worship in 1974 in a home group setting in a congregation I attended during college.