How can we know for sure if Luke is talking about Saturday or Sunday midnight?
7 On the first day of the week, when we were gathered together to break bread, Paul began talking to them, intending to leave the next day, and he prolonged his message until midnight. 8 There were many lamps in the upper room where we were gathered together. 9 And there was a young man named Eutychus sitting on the window sill, sinking into a deep sleep; and as Paul kept on talking, he was overcome by sleep and fell down from the third floor and was picked up dead. 10 But Paul went down and fell upon him, and after embracing him, he said, "Do not be troubled, for his life is in him." 11 When he had gone back up and had broken the bread and eaten, he talked with them a long while until daybreak, and then left. 12 They took away the boy alive, and were greatly comforted. — Acts 20:7-12 (NASB)