Full disclosure here: my Harry Potter re-read isn't going so well. I haven't even finished Philosopher's Stone yet, if we're being completely honest. My excuse is that BookTube-a-Thon took up a week of potential HP reading time, and my newfound obsession with the Throne of Glass series isn't helping much. So I am hereby revoking my promise to have the series done by September. Basically, I'll finish it when I finish it. Definitely Hopefully by January, when my Harry Potter class starts.
One of the things I've noticed so far is that J.K. Rowling is really quite fantastic and placing little hidden eggs throughout the text. It's especially fascinating look at these hints from the perspective of someone who has already read the series, watched the movies, bought the t-shirts, the whole nine yards.