Like it or not, nearly every parish seems to have an Advent wreath. Homes, not so much. The US bishops give this home ritual, in case you and your household are sticklers about it. If you’d like something special for each week, this is a good resource.
Most parishes are sticklers for blessing the wreath at the end of the Liturgy of the Word, after the intercessions. Years ago, I recall most clergy leading this ritual during the introductory rites.
What would you do, were you sitting in the liturgist’s purple armchair? When would you bless? Or would you bother with this optional extra for Advent? Is it something to do at *every* Mass on Advent’s first Sunday? Or just the first Mass?
Catholic Sensibility 
I wish the form of blessing given were more correctly framed as “A Blessing of The Faithful upon The (First) Lighting of An Advent Wreath”