"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." Were these meetings for breaking bread observed any day, or on a specific day?
Acts 20:7
ESV - 7 On the first day of the week, when we were gathered together to break bread, Paul talked with them, intending to depart on the next day, and he prolonged his speech until midnight.
This meeting spanned at least two days by roman reckoning, one or two by jewish. The meeting began the jewish Sunday (our Sat evening or Sun morning) and lasted through to (roman) Sunday or Monday morning. (Acts 20:11) They broke bread at least twice. (Acts 20:7, Acts 20:11) By our reckoning that would be Saturday night (after Sundown) until Sunday day, or our Sunday morning through till Monday morning, since for the jews Sunday begins at our Saturday sunset. The length and time of the meeting was due to "Paul leaving the next day". (Acts 20:7) It was not a restriction on meeting other days, nor even a sign that that was their usual day. It appears he prolonged his message to spend the most possible time with them before he left (Acts 20:7). There was no mandatory day for meeting. The early Christians met on any/every day of the week to fellowship or preach. (Acts 2:42-47, Acts 5:42) 'Breaking of bread' in various verses refers to sharing a meal, which was common, and also the coming together to take communion. It's likely at Paul's meeting that there was both. "Day by day continuing with one mind in the temple, and breaking bread from house to house, they were taking their meals together with gladness and sincerity of heart, praising God and having favor with all the people. And the Lord was adding to their number daily those who were being saved". (Acts 2:46-17) Meeting at houses was common, but they didn't stick to just one house. The believers in a city usually all had fellowship together, and went from house to house. Often it was wealthy widows who would offer up their houses as meeting places. Chloe, for example, was probably one of these widows and thus in a good position to notice warning signs in the Corinthian church (1 Cor 1:10-17). Saul, before he became converted and known as Paul, dragged off the christians from the houses they met at and the synogogues (Acts 8:3-4, Acts 9:2). They also met in the synagogues on the Sabbath, usually to evangelize to the jews (Acts 13:14-44, Acts 17:1-3). The Jerusalem christians could be found regularly at Solomon's Collonade on the east side of the temple (Acts 15:12-15). In Acts 17:1-4 Paul is found preaching for three Sabbaths (Saturdays) in a row. In Acts 13:13-15, Paul goes to the synogogue again. In Acts 13:42-43, Paul comes one Sabbath and then waits and comes back the next to preach. In Acts 16:11-12, the christians go to the riverside to pray, since in that city it was a customary meeting spot. Acts 18:1-4, Acts 18:5-11, etc - scripture explicitly references many Sabbath gatherings. In short: Weekdays they met at houses, the Sabbath they usually at the synagogues if they could. Some historical references: "The primitive Christians did keep the Sabbath of the Jews;.therefore the Christians for a long time together, did keep their conventions on the Sabbath, in which some portion of the Law were read: and this continued till the time of the Laodicean council." The Whole Works of Jeremey Taylor, Vol. IX, p416 (R. Heber's Edition, Vol.XII, p.416) "The ancient Christians were very careful in the observation of Saturday, or the seventh day..It is plain that all the Oriental churches, and the greatest part of the world, observed the Sabbath as a festival...Athanasius likewise tells us that they held religious assemblies on the Sabbath, not because they were infected with Judaism, but to worship [Yahushua], the [Master] of the Sabbath, Epiphanius says the same." Antiquities of the Christian Church, Vol. II, Book XX, chap. 3, Sec. 1, 66.1137, 1138 "Ambrose, the celebrated bishop of Milan, said that when he was in Milan he observed Saturday, but when in Rome observed Sunday. This gave rise to the proverb 'When you are in Rome, do as Rome does,' " Heylyn, The History of the Sabbath, 1613