From January 2 to January 6 — Forefeast of the Nativity of Christ.

Forefeast is one or several days preceding some major Orthodox holidays. They kind of prepare believers for the celebration of the holiday. Forefeast of the Nativity of Christ begins on January 2 and lasts for five days. This is the longest period of the forefeast, thus the Church shows the significance of the event.
The pre-feast of the Nativity of Christ is, first of all, an internal preparation for the general joy - the coming of the Savior into the world. At this time, prayers dedicated to the Nativity are read in the church during the service. The main meaning of all the services of these days is that the miracle of the Incarnation is an act of God's condescension to people. The idea is that the Son of God, having become the son of Man, from the first days of His earthly life enters into a struggle with the forces of evil. The first innocent sufferers for Christ are remembered - the Bethlehem babies, who were exterminated by Herod. On the days of the pre-feast, fasting is intensified. It reaches its greatest severity on Christmas Eve.

Forefeast of the Nativity, Troparion, Tone IV —
Make ready, O Bethlehem!/ Open unto all, O Eden!/ Adorn thyself, O Ephratha!/ For the Tree of life hath blossomed forth from the Virgin in the cave./ Her womb is shown to be a noetic paradise,/ wherein lieth a divine garden,/ eating from whence we live,/ not dying like Adam.// Christ is born to raise up His image which before was fallen.

Kontakion of the Forefeast, Tone III
Today the Virgin cometh to give birth ineffably/ to the preeternal Word in the cave./ Dance, O world! And having heard this,/ with the angels and shepherds glorify// the preeternal God, Who is to appear as a little babe.