My sister was 1 year, 1 month and 1 week older than I.
We both read the Potter books as they came out, and enjoyed them.

One of our annual 'treats' as an expanded family was the trek to see the next Harry Potter film as it came out in theaters. (There were a couple other series we did this with as well, naturally Peter Jackson's renderings of Tolkien's works among them. It became a family 'annual event.')

My sister has now passed, but the memories will always remain.