In its present form the custom of displaying figures depicting the birth of Jesus Christ owes its origin to St. Francis of Assisi, who made the Christmas crèche or manger for Christmas Eve of 1223. The blessing of the Christmas manger or nativity scene may take place on the Vigil of Christmas or at another time that works for your family. When the manger is set up in the home, it is appropriate that it be blessed by a parent or grandparent. https://nolacatholic.org/blessing-of-a-nativity-scene