Saturdays, as good Anglo Catholics will know, is especially associated with the veneration of Saint Mary. In this sense Saturday is unlike other weekdays since they lack such association. Saturday is much more like a Sunday – where the dedication is to the Lord Jesus Christ.
However, in ancient Christian Office books, such as the Portiforium Wulstani, the Saturday is certainly the preferred day to dedicate to Our Lady, but in case the Saturday is occupied by a feast any other day of the week would do. The rule to be followed is that the commemoration of Our Lady would be done on an available weekday closest to Saturday.
To be sure, we are not talking about the Little Office of Our Lady here. The latter is an additional Office to be added the daily office cycle. The Saturday Office is the daily Office enriched with Marian propers. The Little Office is said following the Office of the day.
Fr. Gregory Wassen