That is entirely incorrect. I've read almost every pre-COIE appearance with Wally. The day after he got powers, Wally got up and went school at Blue Valley
High School (unless reprints changed something). Him being 14 and in 9th grade then works well with Dick, who was at least 15 already, and then later seemed a year older than Wally since Dick went to college in 1970 and Wally in 1978 (when Dick was still 18/19). Wally didn't know the Flash was Barry until a year later (real time). He was only visiting Iris for the weekend, it seemed. He got along very well with his parents (who were not prominent characters, I'll grant you), who were good people and good parents (
here's a later, bronze age page and
another). He did not live with Iris, Iris and Barry did not act as his parents. Iris was his aunt, and Barry/The Flash was his friend and later uncle. He also didn't usually act as sidekick - he had a lot more solo adventures than adventures with Barry. He was an independent hero as a teen, which I think is awesome.