Carl announces his Fourth of July party for Friday. This movie was released in early 2002, and most likely filmed in 2001, when the 4th of July was a Wednesday. The thing is, when one of the guests arrives, he says "Happy Fourth of July", so this movie may be set in 2003, when the next Fourth is a Friday, or back in 1997. Sometimes in movies they use a generic date, where the film is not set in any particular year, but is characteristic of a general era.