For a number of reasons, many considers the Epistle of James to be one of the earliest New Testament writings, if not the earliest. For this reason, it is even suggested that it was written prior to the Jerusalem council in Acts 15 over which the James(the brother of Jesus) who wrote the Epistle presided.
In this regard, all of the events recorded in the first 14 chapters (Luke's record is chronological in time) of Acts had occurred, including the martyrdoms of James the Apostle and Stephen, two great 'conversion events' where three and five thousand people were saved, the first at Pentecost and later when the crippled man was healed. The conversion of Saul on the Damascus road, as well as the first Gentile converts in the Ethiopian man and Cornelius.
If it is a little later, obviously more events from Acts would be relevant.