When did the Catholic Church first introduce the veneration of Mary?

There does not appear to be any evidence for Marian veneration during the first and second century. As far as I am aware, the *Didache* (also known as *The Teachings of the Apostles*) and the *Epistle of Barnabas*, both of which tend to be considered first-century, do not mention Mary at all. The phrase "*theotokos*" (God-bearer or the mother of God) seems to be attributed to Athanasius and Gregory of Nazianzus during the fourth century. My understanding is that during the fifth century, the Council of Ephesus (A.D. 431) endorsed the title “*theotokos*.” After this event influential theologians like Augustine of Hippo started focusing even more time and attention on doctrines elevating the position of Mary. Please note that this question is not about whether the veneration of Mary is right or wrong. I simply need to establish the time line of events within the Church that led to the acceptance of the title "*theotokos*" at the Council of Ephesus (A.D. 431) and how the veneration of Mary developed thereafter. EDIT: I found this article on the subject: https://classictheology.org/2021/11/29/the-history-of-mary-veneration-a-protestant-prospective/