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.
Yes, he is the Lord of the one-in-seven day of rest. Paul points out that the law is a guide, and to that end, most, if not all, churches have at least a once-in-seven day of rest with preaching and teaching.
If you are convinced that Saturday is the only possible day for this, then for your conscience sake, you must observe that day, lest you sin. But don’t try to bind other’s consciences on a disputable matter.