Christmas countdowns have been around for as long as we were celebrating Christmas. The first instance of such Christmas countdowns were the Advent Calendars, that are still very popular today.
According to https://christmascountdown.online/, the origin of the Advent Calendar can be traced back to the 19th Century, and the first styles came from the protestant area. The first known Advent Calendar which was made by handwork is from the year 1851.