Mary was fully converted at some point, but I don't think we can be sure about when that was. Surely she was not when Jesus was 12.
Jo kus will answer your long post (I am sure he won't miss how St. Paul uses a future tense conditional in the quote you offer in support of his having been saved in the past).
I recently discovered this rare iconographic type. It is called The Unslumbering Eye of God and it depicts Mary and an angel guarding Jesus as a boy, who rests with his eyes open, while another angel delivers the instruments of His Passion to Him. This is different from better known icons of the Theotokos, where she is holding up Jesus as an infant.
The Unslumbering Eye Savior mid 16c
Maybe Kolokotronis has a better photo.
Another icon that depicts Our Lady near adolescent Jesus is Worthy It Is, where He is delivering the scripture to His Blessed Mother:
