Yes, the first person to call Mary the Mother of My (Adonai) = Lord= God is Elizabeth, Mary’s cousin recorded in the Gospel of Luke 1: 41…
…when Elizabeth heard the greeting of Mary, the baby leaped in her womb. And Elizabeth was filled with the Holy Spirit, 42and she exclaimed with a loud cry, “Blessed are you among women, and blessed is the fruit of your womb! 43And why is this granted to me that the mother of my Lord should come to me? 44For behold, when the sound of your greeting came to my ears, the baby in my womb leaped for joy. 45And blessed is she who believed that there would beg a fulfillment of what was spoken to her from the Lord.”
Peace be with you