The extent to which the Apostolic Church venerated Mary is of doubt and is certainly nowhere near the level at which many venerate her today. Afterall, St Paul and the other Apostles rarely mentioned her in their communications with the various churches. Furthermore, Mary is mentioned only once in the Nicene Creed, and that was only in the affirmation of the Incarnation. If the IC and Assumption are so important, then where are they in the Creeds?
During the lifetime of the Apostles? Sure, I'll grant that. But the earliest known Marian prayer dates back to AD 180, which is pretty early. (The canon of the NT was in flux until around 400.)
Furthermore, Mary is mentioned only once in the Nicene Creed, and that was only in the affirmation of the Incarnation. If the IC and Assumption are so important, then where are they in the Creeds?
First of all, I wouldn't say that they are as important as the truths mentioned in the creeds. Also, remember that the Nicene creed, in particular, was composed in response to the Arian heresy. Not surprisingly, it concentrates on the articles of faith the Arians denied.
The IC required about a thousand years of reflection and theological development. It's noteworthy that St. Augustine specifically exempted Mary from his discussion of original sin, though.
But I can personally attest to icons of her dating to the 4th-7th centuries, still present in ancient monasteries and churches in Georgia. I guess it depends on how early you want to consider the church at that time period.
Only,indeed.