Below is the American Unitarian Reform liturgical calendar for the Christmas Season.

Since this season is not fixed, the ultimate Thursdays for the first two dozenals are not identified on the calendar.  The last dozenal, the Twelve Days of Christmas, has no ultimate Thursday as such.

Advent Eve / Feast of Andrew – (Nov 30) Anticipation of Advent and commemoration of the first disciple of Jesus.

12 Days of Gold – (Dec 1-12) Celebration of Mary’s Motherhood, time for unlit Christmas decorations, and for placing Mary and the Angel in the crèche.
~ 1st Day / Advent / Annunciation / Feast of Eligius – (Dec 1) Commemoration of the revelation of Jesus’ coming to Mary, and celebration of St. Eligius, patron of goldsmiths.
~ Golden Thursday / Observation of Advent– (Ultimate Thursday in the Dozen)
~ 12th Day / Feast of the Virgin of Guadalupe – (Dec 12)

12 Days of Light – (Dec 13-24) Celebration of the Star of Bethlehem, time for lit Christmas decorations, and for placing Joseph and the Star in the crèche.
~ 1st Day / Feast of Lucia – (Dec 13) Celebration of St. Lucia, matron of light and sight.
~ Lightened Thursday / Observation of the Star – (Ultimate Thursday in the Dozen)
~ 12th Day / Christmas Eve – (Dec 24)

Christmas Day – (Dec 25)

12 Days of Christmas – (Dec 26 – Jan 6)
~ 1st Day / Feast of Stephen – (Dec 26) Celebration of the first martyr.
~ 6th Day / New Year’s Eve – (Dec 31)
~ 7th Day / New Year’s Day / Resolution Day – (Jan 1)
~ 12th Day / Epiphany – (Jan 6) Commemoration of the Adoration of the Magi and interfaith communion.