Entirely false. I just provided a link with early Christian writings starting in the last 1st century all referring to worship on the "Lord's Day," aka the first day of the week.
"[L]et every friend of Christ keep the Lord's Day as a festival, the resurrection-day, the queen and chief of all the days of the week. (Ignatius, Epistle to the Magnesians, chp 9. Ante-Nicene Fathers , vol. 1, pg. 62-63.)
It’s still not a divine ordinance. Paul also warned about those in the church who were not followers.