The Sabbath is a one-in-seven day of rest. Six days for labor, one day for rest.
In Acts, the Christian church was established at Pentecost, which was on the same day Jesus rose from the dead, and described by John as the Lord’s Day in Revelation (for, being a Jew, he would have used “Sabbath” if he meant the Sabbath). In 1 Corinthians 16, Paul describes a meet for a collection on the first day of the week. Finally, there is historical evidence that the Jewish Christians went to synagogue on Saturdays, as was Paul’s habit described in Acts, but also met with Gentile Christians on Sundays. This practice was changed when the Christian Jews were excluded from the synagogue.
Why would one try to bind Christians to a standard that the Apostles did not affirm?
What does the Word of God say?
Mark 2:28"Therefore the Son of Man is also Lord of the Sabbath" Here Jesus declares His day for all to know and not guess.
I do not recall any Apostles denouncing Gods Law and replacing it with their own. They were all Jews. They kept the Sabbath (as well as the other Commandments) all of their life. And I am sure unto their death. Acts 18:4 "In the city of Corinth, the Apostle Paul reasoned in the synagogue every Sabbath, persuading the Jews and Gentiles."
I am sure they met other days of the week as well but nothing there suggests a complete overthrow of Gods Commandment.