As the ACNA calendar introduction notes:
Following ancient Jewish tradition, the celebration of any Sunday begins at sundown on the Saturday that precedes it. Therefore at Evening Prayer on Saturdays (other than Holy Days), the Collect appointed for the ensuing Sunday is used.
With today being the 5th day of January, that makes this evening the liturgical beginning of The Epiphany. So when you settle down for Evening Prayer tonight, feel free to start using the Epiphany-specific features, such as: the Opening Sentence (Isaiah 60:30, Nations shall come…). More definitely, the Collect of the Day this evening will be the Collect for the Epiphany:
O God, by the leading of a star you manifested your only Son to the peoples of the earth: Lead us, who know you now by faith, to your presence, where we may see your glory face to face; through Jesus Christ our Lord…
Although the Scripture readings tonight (Jeremiah 4 and Galatians 5) are not chosen to match the feast day, one can observe the bulk of Jeremiah 4’s prophetic description of an invasion of Gentiles as a sort of pre-cursor to the Epiphany. In that reading, the Gentiles are enemies of God’s people; in the Epiphany, Gentiles start becoming God’s people!
Happy twelfth day of Christmas, and enjoy the Epiphany starting tonight.