There's a site that has all the early actions online available to read. I don't know if it's okay to post that here, but checking #30, I'd say I'm not sure that that one counts as definitively flying. While it does mention him "soaring" at one point, that doesn't necessarily mean he was soaring due to being able to fly, it could just be describing a big leap. In #60, lois lane gains superman's powers (although it looks just to be a dream sequence), but she certainly does appear to be flying, as it shows her path through the sky in one panel and she's zipping back and forth between buildings and circling buildings. In #65, a kid asks superman "lets see you fly", and in the next panel it's possible he is flying off, but its also possible it's just a leap. In 67 he sure looks to be flying given the arcing paths he takes through the sky.