The revelation of the Trinity was already given to Mary at the Annunciation

On August 15, 1988, in his Apostolic Letter On the Dignity of Women and in continuity with the Fathers of the Church such as Gregory Thaumaturgust, Pope John Paul II asserted that the revelation of the Trinity was already given to Mary at the Annunciation. This revelation allowed Mary to attain an unparalleled union with God through the power of the Holy Spirit. At the same time, it manifested the dignity of the woman and the authenticity of her freedom:

“The self-revelation of God, who is the inscrutable unity of the Trinity, is outlined in the Annunciation at Nazareth. "Behold, you will conceive in your womb and bear a son, and you shall call his name Jesus. He will be great, and will be called the Son of the Most High" - "How shall this be, since I have no husband?" - "The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy, the Son of God... For with God nothing will be impossible" (cf. Lk 1: 31-37). [...]

Thus the "fullness of time" manifests the extraordinary dignity of the "woman". [...] Through her response of faith Mary exercises her free will and thus fully shares with her personal and feminine "I" in the event of the Incarnation. With her "fiat", Mary becomes the authentic subject of that union with God which was realized in the mystery of the Incarnation of the Word, who is of one substance with the Father. All of God's action in human history at all times respects the free will of the human "I". And such was the case with the Annunciation at Nazareth (1).”

Françoise Breynaert

John Paul II, Apostolic Letter Mulieris dignitatem, on the dignity and vocation of women, § 3-4