Didn't see or think of it that way before, that would put it back to Sunday, right?
Act 16:13 And on the Sabbath day we went out of the city to the riverside, where prayer was customarily made; and we sat down and spoke to the women who met there.
Act 17:2 Then Paul, as his custom was, went in to them, and for three Sabbaths reasoned with them from the Scriptures,
Act 17:3 explaining and demonstrating that the Christ had to suffer and rise again from the dead, and saying, "This Jesus whom I preach to you is the Christ."
These were Gentile cities and he was teaching the Gentiles. Why not on Sunday? Why did he teach them on the Sabbath?
Act 18:4 And he reasoned in the synagogue every Sabbath, and persuaded both Jews and Greeks.
Notice both Jews and Gentiles on the Sabbath.
Act 13:42 So when the Jews went out of the synagogue, the Gentiles begged that these words might be preached to them the next Sabbath.
Act 13:43 Now when the congregation had broken up, many of the Jews and devout proselytes followed Paul and Barnabas, who, speaking to them, persuaded them to continue in the grace of God.
Act 13:44 On the next Sabbath almost the whole city came together to hear the word of God.
Now here was a golden opportunity to tell the Gentiles to come back tomorrow, the first day of the week but he didn't. He taught them on the next SABBATH. The Sabbath has never been changed.
In Acts 15 when a great controversy arose over physical circumcision, it required a headquarters conference of the Church to settle it. There is no such controversy in the New Testament over the Sabbath. Why? Because the day God made holy at creation has never been changed. Christ is still Lord of the seventh day Sabbath.