I stated that the Sabbath is the 7th day of the week, which is Saturday. You stated that Constantine set the days of the week even though the Romans had ben switching from the 8 day week to the 7 day week long before Constantine. Here is more discussion on the subject. I don't know how credible the writers are.
Why Are There Seven Days in a Week?
The Origin of the Jewish Week | Nature
1939PA.....47..175C Page 175
From the link you gave -
" Now, whatever may be the ultimate solution of the problem of the origin and diffusion of the seven-day week, this theory rests partly on uncertain assumptions, partly on undoubted blunders. It is notorious that several Semitic nations, not to speak of the Peruvians, had a seven-day week without planetary names; so that Mr. Proctor's fundamental assumption begs the whole question. Then, again, it is the opinion of so great an authority as Lepsius that the Egyptians had no seven-day week, but divided the month into three decades. The passage of Dion Cassius from which the contrary opinion is drawn is certainly not decisive for ancient Egyptian usage, and Mr. Proctor seems to quote his author at second hand; for he asserts, in flat contradiction to Dion, that when the latter wrote, neither Greeks nor Romans used the week. For the supposition that Saturn was the supreme god of the Egyptians, not a shadow of proof is offered, while what is said of the Assyrian Saturn is directly in the teeth of the most recent researches. If Mr. Proctor had read Schrader's essay on the Babylonian origin of the week, he would have known that Adar or Saturn is quite distinct from the supreme god Asur. Thus, apart from the late and doubtful testimony of Dion, Mr. Proctor has no other evidence for his Egyptian theory of the week than that which he derives from the presumed non-existence of the Sabbath among the Hebrews before they entered Egypt. But the seven-day week appears in the narrative of the flood, which is certainly not an Egyptian legend. I say nothing of numerous minor inaccuracies in Mr. Proctor's paper, but repeat that the point on which new light requires to be thrown is whether it can be made out that the names of the seven days are as old as the week itself. This again seems to depend partly on the question whether the division of the day into twenty-four hours is older than the week, and partly on what can be determined as to early Egyptian and Chaldean subdivisions of the month. The Egyptians had a day of twenty-four hours, but had they a week? The Chaldeans may have had the week, but they seem to have divided the day (including the night) into twelve hours. Perhaps, however, it ought to be borne in mind that Dion gives another way of accounting for the names of the day, depending not on the division of the day into hours, but on the analogy of musical harmony .
The Jewish Sabbath can contribute little to the argument unless one is prepared with Lagarde to maintain that Shabbat is a name of Saturn."
^Makes my point essentially in saying there is no evidence for the Shabbat to be on Saturday outside of historical assumptions and it being connected to Constantine's decree for Sunday to be the first day of the week
1939PA.....47..175C Page 175
^ This link again supports my claim by stating although there might have been a 7-day week before Constantine the actual order of the days were different with Saturday being the first and Friday being the last in some cases.
Some sources to back my claims-
These . . . eventually led Jewish rabbis to call Saturn “Shabbti,” “the star of the Sabbath.” It was not until the first century of our era, when the planetary week had become an established institution, that the Jewish Sabbath seems always to have corresponded to Saturn’s Day [Saturday]. Rest Days, p.244 by Hutton Webster
This planetary week was paganism’s counterfeit of the true, Biblical week instituted by the Creator in the beginning of earth’s history. In the counterfeit week employed in ancient paganism
“the venerable day of the Sun” was esteemed by the heathen above the other six days because it was regarded as sacred to the Sun, the chief of the planetary deities . . .
Just as the true Sabbath is inseparably linked with the Biblical week, so the false Sabbath of pagan origin needed a weekly cycle. Thus we have found that the planetary week of paganism is Sunday’s twin sister, and that the two counterfeit institutions were linked together … Odom,
op. cit., p. 243-244, emphasis supplied.
“The long-term effect was that
‘Easter Sunday’ entered the Christian paradigm as ‘The Day of Christ’s Resurrection.’
The corollary to this realignment of time calculation was that the day preceding Easter Sunday, Saturday, became forever after the [perceived] ‘True [seventh-day] Bible Sabbath.’ This is the true significance of Constantine’s ‘Sunday law’ and it laid the foundation for the modern assumption that a continuous weekly cycle has always existed.”
eLaine Vornholt & Laura Lee Vorholt-Jones, Calendar Fraud, “Biblical Calendar Outlawed.”