According the this site aaanime.net
the movie takes place between episodes 22 and 23.
I recently got my friend hooked on the show. In less than a week he has watched the entire series and I just lent him the movie today. I noticed that most people who don’t really like anime do enjoy this show. I refused to watch for years but then a friend made me watch some episodes he had on dvd and I’ve been thanking him for it ever since.