However, as is confessional for my own church, I hold that the change occurred in Acts, as a result of the resurrection of Christ on the first day of the week (as I have written before; use the "sabbath" tag below). This is testified in the Apostolic Fathers, such as the Epistle of Barnabas, which dates, at least, from the Second Century. It may have been written by Saint Barnabas, who figures prominently in Acts.
After citing Isaiah 1:13, the author tells us that the practice of the Christians, in honor both of Christ's resurrection and ascension, gathered on the eighth day, which would be the first day of the following week. He uses "eighth day" instead of "first day" because of the prophecies of such, e. g., Leviticus 22:27, 23:11, 23:36, and especially the Feast of Pentecost in Leviticus 23:15-16. Notice the repeated references to the eighth day in the context of atonement!
This epistle, while not Scripture, nevertheless indicates that it was the practice of the church to celebrate the first day of the week, not the seventh. And, thus, the claims of the Adventists are erroneous.