After the annual celebration of the Paschal Mystery, the Church has no more ancient custom than celebrating the memorial of the Nativity of the Lord and of his first manifestations, and this takes place in Christmas Time
The Vigil Mass of the Nativity is used on the evening of 24 December, either before or after First Vespers (Evening Prayer I). On the day of the nativity of the lord, following ancient roman tradition, Mass may be celebrated three times, that is, in the night, at dawn and during the day
The Sunday falling between 2 January and 5 January is the second Sunday after the nativity. The epiphany of the lord is celebrated on 6 January, unless, where it is not observed as a holyday of obligation, it has been assigned to the Sunday occurring between 2 and 8 January.