Normaly on the 1st day of the fast(just as with the Apostles Fast),NO LIturgy is served. This year, for those of us on the Julian Calendar, the fast began on Thanksgiving. I served a Matins with First Hour, doing the Prayer of St. Ephraim the Syrian.
Of course, should the fast begin on Saurday or of course on Sunday, Liturgy would be served and the Lenten form of service disregarded. Since the Apostles Fast always starts on a Monday, the Lenten type of service would be the norm, but only on the first day. At least, that's the current Orthodox practice.