After introductory versicles, begin the Rosary with the "Hail, Holy Queen", its usual versicle and the collect "O God, Whose Only-begotten Son" – this was the somewhat startling advice I found in several late nineteenth century books, said to follow the official method laid down for use amongst Dominicans.
These days, of course, one expects to say such prayers at the end of the decades (Dominicans still maintain the introductory versicles, instead of the newfangled Creed, Lord's Prayer and three Hail Mary's); then, instead, they were said beforehand, and afterward – where now they are recited – instead came first the Litany of Loreto, and then the Sub tuum and an anthem to St Dominic, with appropriate versicles and collects.
The collect connected to the Sub tuum in this arrangement seemed familiar, as I have seen it referred to as St Pius V's prayer for use at the conclusion of the Rosary – the more familiar "O God, Whose Only-begotten Son" having been introduced by his successor, Gregory XIII, when he approved a proper Mass and Office for the feast of the Rosary. But the prayer appointed by St Pius V is itself a modification of the Dominican collect for Marian feasts – unsurprising, as Pius was a Friar Preacher:
Supplicationem servorum tuorum, Deus miserator, exaudi, ut, qui in societate sacratissimi Rosarii Dei Genitricis et Virginis congregamur, ejus intercessionibus, a te de instantibus periculis eruamur. Per eumdem Christum Dominum nostrum. R/. Amen.
(Hear, O merciful God, the prayer of thy servants: that we, who meet together in the Society of the most holy Rosary of the Virgin Mother of God, may, through her intercession, be delivered by thee from present dangers. Through the same Christ our Lord. R/. Amen.)
Having come across this old form, I now preface the Rosary with the Sub tuum, versicle Post partum and collect Supplicationem servorum quorum, plus – from what I've learnt from our local Monday night Rosary group – the Memorare, before I make the usual start by signing myself with sign of the Cross, saying the Creed, and so forth.
Spanish sources gave a variant to the Dominican or rather "Pian" collect for the Sub tuum (which they paired with the collect of the Angelus for good measure), which I prefer, as it is not so much that we meet together in a society of the Rosary as instead meet to recite it – hence its use in the version given below (Dominicans omit "gloriosa et" in the Sub tuum, by the way):
Aña. Sub tuum presidium confugimus, sancta Dei Genitrix: nostras deprecationes ne despicias in necessitatibus, sed a periculis cunctis libera nos semper, Virgo gloriosa et benedicta.
V/. Post partum, Virgo, inviolata permansisti. R/. Dei Genitrix, intercede pro nobis.
Oremus.
Supplicationem servorum tuorum, Deus miserator, exaudi: ut, qui ad recitandum sanctissimum Rosarium Dei Genetricis et Virginis Mariæ congregamur, ejus intercessionibus a te de instantibus periculis eruamur. Per eumdem Christum Dominum nostrum. R/. Amen.
Ant. We fly to thy patronage, O Holy Mother of God: despise not our petitions in our necessities, but ever deliver us from all dangers, O glorious and blessed Virgin.
V/. After childbirth, O Virgin, thou didst remain undefiled. R/. Mother of God, intercede for us.
Let us pray.
Hear, O merciful God, the prayer of thy servants: that we, who meet together to recite the most holy Rosary of Mary, Mother of God and Virgin, may, through her intercession, be delivered by thee from present dangers. Through the same Christ our Lord. R/. Amen.
