Our own Harry Potter

Last weekend S and D went to a Harry Potter class at the Children's Museum. D made a wand, hat, and cape. They took lessons in transfiguration (transforming milk into a solid) and also did some Muggle studies. D has yet to see a Harry Potter movie, but S and I are big fans. Not sure at what age we should introduce him to the movies...or should we wait until he is old enough to read the books. Anyone?