Maybe 13 days later. An announcement page can be created at any time. We would need to see the Microfiche to know.
Just a thought, from his book he said that he remembered the time of his birth from the BC he found in the attic as a youth. 7:24 PM. Could that actually be he found the date, 7/24, was something different than he’d been told?
Finding a new birthday would certainly be more memorable than a time of day, wouldn’t it?