Those that keep the first day of their week as the Sabbath using Acts 20:7, are standing on a false foundation of deception in translation, as so obviously depicted below.

King James Version 
Act 20:7 And upon the first day of the week, when the disciples came together to break bread, Paul preached unto them, ready to depart on the morrow; and continued his speech until midnight.

New International Version
On the first day of the week we came together to break bread. Paul spoke to the people and, because he intended to leave the next day, kept on talking until midnight.

Correctly translated it should be:
And on one of the sabbaths, having been assembled the disciples to break bread, Saul reasoned to them, being about to depart on the morrow; he continued the discourse until midnight.

 Acts 20:7 from Jay P. Green Sr. Interlinear

#4521 in Strong's Concordance

Strong's 7676

Strong's 7673

Acts 20:7 in part in Nestle Greek Interlinear

Image from Young's Analytical concordance of the Bible
page 89 in index at the end of the book.


Images from Young's Analytical concordance of the Bible page 829

Acts 20:7 Hinds & Noble Greek Interlinear