In the Bible, seven consecutive weekly sabbaths corresponds to forty-nine days:
“And ye shall count unto you from the morrow after the sabbath, from the day that ye brought the sheaf of the wave offering; seven sabbaths shall be complete: Even unto the morrow after the seventh sabbath shall ye number fifty days; and ye shall offer a new meat offering unto the LORD." Leviticus 23:15-16
To further establish this, the seven weekly sabbaths or 49 days was paralleled with seven sabbaths of years or 49 years marking the Jubilee:
“And thou shalt number seven sabbaths of years unto thee, seven times seven years; and the space of the seven sabbaths of years shall be unto thee forty and nine years. Then shalt thou cause the trumpet of the jubileb to sound on the tenth day of the seventh month, in the day of atonement shall ye make the trumpet sound throughout all your land. 10 And ye shall hallow the fiftieth year, and proclaim liberty throughout all the land unto all the inhabitants thereof: it shall be a jubile unto you; and ye shall return every man unto his possession, and ye shall return every man unto his family.” Leviticus 25:8-10
So there was a perfect synchronization: the 7th day Sabbath WAS NOT any day immediately following any six-day period. Also, the fact that seven consecutive weekly sabbaths corresponds to forty-nine days totally debunks the “Lunar Sabbath” deception.
I have never found any evidence of a pre-Constantine seven-day calendar that depicted the seventh day as Saturn’s day.
We know that around that time, the Church of Rome forbade Christians to keep the 7th day Sabbath and urged them to keep the first day of the week instead in honor of the resurrection, and that the first day of the week was also known as “the venerable day of the Sun” a.k.a Sunday.
So it is not that difficult to know what day is the Sabbath. But beyond the issue of the actual day of worshup is the issue of authority and allegiance since the setting aside of the 7th day Sabbath in favor of Sunday was the illegitimate act of a human power usurping divine authority.
“Christians must not judaize by resting on the Sabbath, but must work on that day, rather honouring the Lord’s Day ; and, if they can, resting then as Christians. But if any shall be found to be judaizers, let them be anathema from Christ.” Canon 29, Council of Laodicea (363-364 AD).
“On the venerable Day of the Sun let the magistrates and people residing in cities rest, and let all workshops be closed. In the country, however, persons engaged in agriculture may freely and lawfully continue their pursuits; because it often happens that another day is not so suitable for grain-sowing or vine-planting; lest by neglecting the proper moment for such operations the bounty of heaven should be lost.” Constantine I, Decree (7 March 321 AD)