When was Blessed Virgin Mary first chosen as Jesus' Mother?

I came across a short prayer appended to the Holy Rosary, which states that Blessed Virgin Mary had been chosen from the very beginning, to be the Mother of Jesus. Though the curse given to Satan in Genesis speaks of the progeny of woman crushing the Devil's head, it needs to be confirmed that God the Father had Mary in mind. Some references state that Mary was, at the fulfilment of time, chosen to be the Mother of Jesus. My question therefore is : **According to Catholic scholars, when was Blessed Virgin Mary first chosen as Jesus' Mother?**