It makes such a difference. Sending a greeting a day or two early or late – I dislike it when I do so (in error of course).
But sometimes calendars “go wrong”. The old paper type were reliable, after all what event would transpose December one year to appear as January the next? Well, “at least it would be human error”.
This seems unimportant. That’s until the Superbowl or the World Cup soccer finals happen on the day nobody expects! Now you understand!