Which 7th day is correct
for the Shabbat?

The six working days, the day of Shabbat,
the day of Chodesh (new month):
Eze. 46:1 Thus says YHWH Elohim, The gate of the inner court facing east shall be shut the six working days; but it shall be opened on the day of Shabbat and opened on the day of the Chodesh
In this case, it has to be the renewed lunar weekly cycle starting after the 1st day of every Chodesh (lunar month), toward the Shabbat days on the 8th, 15th, 22nd, and 29th. Every lunar month has 4 weeks of six working days and the day of  Shabbat [4x7=28; from 2nd day to 29th day of month] plus a day of Chodesh or two if necessary [1st day, 30th day (necessary)]Isa. 66:23 And it shall be from Chodesh to Chodesh and from Shabbat to Shabbat, all mankind will come to bow down before Me, says YHWH.  Amos 8:5 explains how to observe every Chodesh and its Shabbats separated from all the working days. 
Isa. 66:22 tells that there are two cycles: monthly cycle and weekly cycle.  Eze. 46:1 obviously shows there are two different cycles because we know there is a weekly cycle of six working days and 7th day Shabbat.  The day of Chodesh cannot be in the weekly cycle, but in the monthly cycle!  Therefore it is a lunar month for all the Shabbat days are counted from the beginning of lunar month.  Also the gates are open for the days of feasts (moadim) in Eze.  46:9.

When will the Chodesh (day of new month) be over....
the (day of) Shabbat (be over)?:
Amos 8:4-6 Hear this, you who  trample the needy, to do away with the humble of the land, saying, When will the Chodesh be over, So that we may sell grain, And the Shabbat, that we may open the wheat market, To make the bushel smaller and the shekel bigger, And to cheat with dishonest scales, So as to buy the helpless for money And the needy for a pair of sandals, And that we may sell the refuse of the wheat?; Isa. 66:23: “And it shall be from Chodesh (Full/New Moon) to Chodesh (Full/New Moon) And from Shabbat to Shabbat, all mankind will come to bow down before Me, says YHWH.”
When the Chodesh will be over depends on the 4th (last) Shabbat that is on the 29th of lunar month.  The 4 Shabbats (8th, 15th, 22nd, 29th) are within its lunar month.  Therefore there is only one lunar calendar mentioned in the whole Scriptures!  Why they need to know when the Chodesh is over because it may needs one or two day Chodesh observation depending on the rising of the mature full moon after the sunset?
See that the day of Shabbat is always depending on the count down from the head of Chodesh!

8th, 15th, 22nd, 29th days of Shabbat every lunar month:
Lev. 23:5-7 Then on the fifteenth day of the same month there is the Feast of Unleavened Bread to YHWH, for seven days you shall eat unleavened bread.  On the first day you shall have a holy convocation; you shall not do any laborious work.  Num. 29:12 Then on the fifteenth day of the seventh month you shall have a holy convocation; you shall do no laborious work, and you shall observe a feast to YHWH for seven days.  Esther 9:18 But the Jews who were in Susa assembled on the thirteenth and the fourteenth of the same month, and they rested on the fifteenth day and made it a day of feasting and rejoicing.
The lunar Shabbat rest days are written in the whole Scriptures as the 8th and 15th days of the lunar months are known to many.  The 15th day of 1st month for the feast of Unleavened bread, the 15th day of 7th month, the 15th day of 12th month for the feast of Purim (Esther 9:18) are known as the non-work Shabbat days every year.  Even the second Passover for those uncleaned who were not prepared for 1st Passover, yet there is a fifteenth day of 2nd month as the non-work Shabbat day, for the Passover is the 14th day prepared for the feast of Unleavened Bread.
Isa. 66:23 reminds all of us that the weekly cycle (six working days and 7th day Shabbat [Eze. 46:1-3]) is reset by the monthly cycle (head of moon), in which we, the spiritual minded (keepers of His instructions), dwell restfully in the eternal Kingdom/cycle of His Light/Chodesh (full moon to full moon), in opposition to the fleshly minded (the lawless ones) that dwell in the cycle of the darkness (dark moon to dark moon) without rest.  We always look His Light and dwell in His rest, for He is our Light to behold and the Master of Shabbat.

The cycle of His Light (Full Moon) and Rest (Shabbat)
for His chosen ones to enter:
Isa. 66:23 And it shall be from Chodesh to Chodesh and from Shabbat to Shabbat, all mankind will come to bow down before Me, says YHWH. It speaks of two different cycles: from Chodesh to Chodesh [29-30 day intervals] and from Shabbat to Shabbat [7-day intervals], since the one or two-day Chodesh is not included in the "from Shabbat to Shabbat" cycle.
From Shabbat to Shabbat is the cycle of forwardness to begin and to end at the sunset (westwardness) so is the same cycle of forwardness from the Chodesh (full moon) to Chodesh.  The sunrise is the beginning of day (eastward) and the sunset (westward) is the end of day, so the rising of full mature moon is the beginning of month (night) at east, for the sun rules the day and the (full) moon rules the night.

His fixed lunar order for man to follow the cycle of Chodesh
(new month) and the cycle of Shabbat:
Jer 31:35-36 Thus says YHWH, who gives the sun for light by day and the fixed order of the moon and the stars for light by night, who stirs up the sea so that its waves roar; YHWH of hosts is His name: If this fixed order departs from before Me, declares YHWH, then the offspring of Yisrael also will cease from being a nation before Me forever.  Amazingly, how forgetful many go astray from keeping His fixed order of moon, for the sake of keeping the Babylonian (Gregorian) calendar.  Remember that the tribes of Yisrael were carried to the 70-year Babylonian captivity and kept their solar calendar of named planets and legends.  Those, returned back to the land of Yisrael after that captivity, did work on the Shabbat days of its lunar cycle but were later corrected and restored back to His fixed order (Neh. 13:15-22).   A few keep His fixed order of  moon today but many go after the men's traditions of keeping what is fixed order of the sun.   The Shabbat is easy to follow within a lunar cycle beginning with its Chodesh (full moon), but it cannot follow within a solar cycle.  It is understood that the sun is for the daylight, the stars is for the night light, and the moon is for the fixed order of lunar cycle that gives us the Chodesh and its Shabbats, and even its festival seasons within.  The reason is why many are scattered in this world as the lost tribes of Yisrael that need to restore back to His fixed order and to make us a bond of His Nation of Yisrael!