For some time I have surmised that the mention of a "jezebel" in the church at Thyatira (Rev. 2:20f) is proof that women served as leaders of churches from the beginning. They did not have to be perfect, neither then nor now! Also, there is the hint in I Corinthians 1 of "Chloe's people" i.e. of the church she led. And there is Junia the apostle in Romans 16:7 who was "prominent among the apostles..."