Historically, if you include the NT. You have yet to show us all a place in the NT where the early church post resurrection met on the last day of the week.
Act 18:4 And he reasoned in the synagogue every sabbath, and persuaded the Jews and the Greeks.
Jews and non-Jews alike knew that on the sabbath the word of God was to preached.
Act 17:2 And Paul, as his manner was, went in unto them, and three sabbath days reasoned with them out of the scriptures,
It was Paul's custom to preach on the sabbath.
Act 16:13 And on the sabbath we went out of the city by a river side, where prayer was wont to be made; and we sat down, and spake unto the women which resorted thither.
Christians going down to the river to pray on the sabbath.
Act 13:42 And when the Jews were gone out of the synagogue, the Gentiles besought that these words might be preached to them the next sabbath.
Interesting how the gentiles *expected* to be preached to on the sabbath.
Act 13:44 And the next sabbath day came almost the whole city together to hear the word of God.
The first mega-church?
Again, you are arguing from what you presently believe and are extending it back to biblical times. Remember, the ONLY scripture they had was the "old" testament. The 7th day sabbath was one of the normative, commanded days to come together and worship the Lord God. The thought of NOT keeping the sabbath never crossed anyones mind. It wasn't even an issue in the bible. Compare that to the issue of not physically circumcising gentiles. That was a HUGE issue that required a church council to decide and it was well documented in Acts.
Surely if Paul or any other Christian were breaking the sabbath they would have been accused by the Jews of doing so. Yet not one mention of it in all of scripture. Curious don't you think?