Remember that Lutheran Service Book Agenda includes a rite for "Blessing of the Advent Wreath" on pp. 309-310 for use on the First Sunday in Advent. It includes these words:
"Beloved in the Lord, as we begin the season of Advent, let this wreath remind us that Jesus Christ came to conquer the darkness of sin and to lead us into the light of His glorious kingdom. As the prophet Isaiah says, 'The people who walked in darkness have seen a great light; those who dwelt in the land of deep darkness, on them has light shined.'"
The prayer in the rite includes the petition:
"enkindle in our hearts the fire of Your love that we may receive You with joy and gladness."