I feel like Harry Potter became mainstream/popular in my area roughly around the release of the third book. Or at least that’s when I remember becoming aware of the series. I was in elementary school and attended a small non-denominational christian school. It kind of just depended on the families, some were fine with it, like mine was. My mom read the first book to my younger brother and I as part of our nightly reading together. It was just emphasized that this was a fun fictional story and not real. There were other families who didn’t like the concept of magic but were otherwise ambivalent, and of course some were convinced it was all a ploy by satan trying to convert children to witchcraft. The details are all pretty fuzzy, but I think the stances generally tended to follow the denomination of the family, but not always.