Saying the Liturgy of the Hours, the Church's prayer, during many seasons can be complicated and challenging to the novice. Use of a liturgical calendar can be very helpful.
In the past it seemed that just about every household displayed a calendar upon which were listed all of the saint's feast days as well as the Solemnities and Holy Days of obligations,as well as the national holidays and more mundane fare. In the present time, it seems that many Catholic households do not follow this practice, and it is few and far between the student who can name the particular saint's feast of any given day.
The Octave of Christmas is rather unique in the Liturgy in that the Invivatory, the Morning prayer, and other readings are taken from the feast days, but the Evening Prayer is taken from the seasons. The antiphons and psalms for the evening are taken from Evening Prayer II on Christmas day, while Night Prayer is taken from Sunday Prayer II.
So except for Holy Family Sunday, which has its own readings, during the Christmas Octave, for the Church, time effectively stops. In our joy we repeat the Evening Prayers, or at least parts of them through the whole Octave. Our joy at the birth of Our Lord, His Incarnation into human flesh is so great it cannot be constrained to single day or even a single week.
And so one must keep in mind the day, the date and the position of Christmas and Holy Family Sunday in the rythm of the Calendar.