So, you agree that God extended His Grace to Mary BEFORE the Annunciation and obviously BEFORE the Crucifixion and Resurrection. This is a good start.
So, now that we are all in agreement that Mary's salvation was assured and God's Grace was upon her BEFORE the Crucifixion and Resurrection, can you explain why it couldn't have occurred at the moment of Mary's conception? Can you give a time that makes more sense?
I already did. When God decided that it was time to send the Messiah to Israel, there may have been several candidates for mother, but God chose Mary at that time just before sending Gabriel to tell her -- not before that. Why is that not plausible??? Do you think that Mary was the only virgin in Israel descended from the line of David?
I know I'm stepping into the middle of a different conversation.
The impartation of God's grace on Mary is not the same as her salvation being assured. Of course, I am of the opinion that all those saved are saved before the foundation of the world, because God chooses who to be saved and does so before the foundation of the world.
So in one sense, every one of the elect, chosen by God, are "without sin" from the moment of conception.
But that is not what is asserted in the narrative of Mary being sinless. The claim is of some special sinlessness.
God's sacrifice of his only Son was necessary for salvation. If it was not, if God could in other ways rid us of sin, then the murder of his Son would not be a great sacrifice, but a horrible waste.
If Mary could live a sinless life without Jesus, then God could have granted all his elect a sinless life, without Jesus.
Of course, I take the meaning of God's Grace being upon Mary in the same way I take other uses of the same word in the Bible, not as some unique "Grace" given to no other.