The last post, The Christmas Calendars, described how the transition is made between the season of Christmas, which reckons time in days after Christmas, and Ordinary Time, which reckons it in weeks starting on a Sunday.
There are two options at this time: the religious and the commercial. The religious calendar celebrates the Epiphany on 6 January, so the transition from Christmas to weeks happens after the Epiphany season. The commercial calendar celebrates the Epiphany on the Sunday between 2 and 8 January, so the transition from Christmas to weeks happens before the Epiphany season. The last post had a couple of elegant tables to show how it all works.
With adjustments to calendars come adjustments to liturgies. 6 January (when not the Epiphany) and 7 January (before the Epiphany) are days that are not part of the religious calendar, and yet they need to have a liturgy. The last post described how these liturgies were put together.
That is how things work in the whole world, both in the original Latin and in English translation. However, the American translation is different, and wrong.