Should Christians Keep Sunday Holy and call it the "Lord's Day"?
In any discussion of the issue of whether the early church observed the first day of the week or the seventh day of the week as the Sabbath day, it is a very good idea to take a look at Acts 20:7. Notice that Acts 20:7 states that they met together on Saturday evening, had a meal together, and then the text states that Paul preached until MIDNIGHT because Paul was going to leave the NEXT DAY. At midnight the young fellow, Eutychus, fell out of the window and was revived by Paul.
Paul then preached until daylight (the reader must remember that days of the week in the Bible began at sundown and ended at sundown — from evening unto evening: see Genesis 1). Thus the "first day of the week" began at sundown on Saturday evening.
Here is the TEV's correct translation of Acts 20:7,11
"vs.7. On Saturday evening we gathered together for the fellowship meal. Paul spoke to the people and kept on speaking until midnight, since he was going to leave the next day.......vs.11. After talking with them for a long time, even until sunrise, Paul left."
Notice that Paul, after preaching all night, left on SUNDAY morning for his journey. He and the believers DID NOT then have a Sunday morning church service. The first day of the week was of no religious significance to the first century church: see "Sunday and the Early Church".