When is Zack and Codys birthday?

Cole and Dylan Sprouse, aka Zack and Cody Martin, were born August 4, 1992. The birthday of the characters was said to be a Sunday in 1992, with no specified date. There is a video of the twins as babies dated September 23, 1992 (a Wednesday).

(search for either may turn up actual persons named Zack Martin and Cody Martin, unrelated)