Mary was “full of grace” since conception. Grace is an action of the Holy Spirit. The Holy Spirit dwelt within Mary fully from the moment she was conceived.
The Holy Spirit dwelt with Mary in a very special way, as her spouse, from the moment of the annunciation, when She was overshadowed by the Spirit and Jesus was conceived.
The Feast of The Presentation of the Blessed Virgin Mary is celebrated every Nov 21. The Eastern Catholic Churches call this feast the Entrance of the Theotokos. Sacred Tradition teaches that Mary, when she was three years old, was brought into the temple by her parents Joachim and Anna, to be educated and dedicated as a temple virgin. Zechariah, the father of John the Baptist was high priest at the time. Zecharia brough Mary into the temple and she ran up the steps, into the Holy Place, right through the curtain, and into the Holy of Holies where she danced before the Ark of God. She didn’t want to leave the Temple after that unless she were betrothed or died. Mary brought the Holy Spirit with her into the Temple.
There is a hymn in the Eastern Catholic Churches which goes.
*The most pure Temple of the Savior;
The precious Chamber and Virgin;
The sacred Treasure of the glory of God,
Is presented today to the house of the Lord.
She brings with her the grace of the Spirit, *
Therefore, the angels of God praise her:
"Truly this woman is the abode of heaven.