When Christ died on the cross and rose from the dead as the Firstfruits on Sunday, this became the Sign of the New Testament Sabbath (our resurrection in Christ). When His "work" was completed, He rose from the dead our New Sabbath of rest on Sunday. It became our New Testament day of rest. This is just as God ended His work and rested on Saturday in the beginning, the Old Testament day of rest. We no longer are to rest on the Old Testament Sabbath (which would put us under the law), but the on New Testament Sabbath, illustrating our Sabbath (rest) from work is in Christ's resurrection. Not under law, but Grace! We read in,
It was the end of the Old Testament Sabbaths, and the dawning of the New Testament Sabbaths. In your Bible it may read first of the "week" (an unfortunate translation) but the word there is Sabbaths [sabbaton] from the root Hebrew word [Sabbath]. In that verse, the two words, one translated "week" and the other "Sabbath," are the identical words, the plural of [sabbaton]. Sabbaths! We can understand why translators made this error, as it doesn't "seem" correct to say, "in the end of the Sabbaths (plural), as it began to dawn towards the first of the Sabbaths (plural)". But when we understand that it was speaking of an end to the Old Testament era of Sabbaths and the beginning (dawn) of a New Testament era of Sabbaths, it makes perfect sense. We can readily understand (though not condone) why they decided to translate one sabbaton as week and the other identical sabbaton as Sabbath (singular), but in the Greek they both are the identical plural words Sabbaths. This is confirmed by Greek scholars, and there is nothing in the Greek which would promote the translating these same two plural Greek words for sabbaths, differently here.
Unfortunately, as we all know, even translators make mistakes sometimes. We all have feet of clay, we're all human. But marvelously, God has preserved the Greek from which the translations were made, so that we can check every translation and every new version of the Bible ourselves to "test" it's accuracy. We can test any translation with the Greek and Hebrew from which it is taken, to make sure the translation is an accurate one.
Note the language of Matthew, and carefully consider what is actually said. This is not incidental language here. As the old adage goes, "God knows what He is doing, even when we do not!" It says, "at the End, or Close of the Sabbaths, as it began to Dawn towards the FIRST of the Sabbaths". ..Think about that. Why would God say the end of the Sabbaths, as it dawns toward the FIRST of the Sabbaths? Has God ever used this type language before? The answer is No! Has God ever said at the end of one weeks as it began to dawn towards the first of another weeks? ..Again, no, never! Because never before had Christ been Crucified, completed His Work on the cross, and risen the dawn of a new DAY, wherein we have our rest from work! A New Testament Sabbath of rest for us. That's why God says at the end of the Sabbaths, as it began to dawn towards the first of the Sabbaths. It's because one era of Sabbaths (7th day) representing the Old Testament is ending, and another (8th day, Sunday) is the "FIRST" of the dawn of another era of Sabbaths representing the New Testament. The ending of the Old, and the beginning of the New. When Christ arose that 8th day (Sunday), a new era of Sabbaths had begun IN HIM! Not a New Sabbath, but the completion/fulfillment of the Sign of the old! God's Word isn't made up of incidental or coincidental language, it's all inspired, God Breathed, and Deliberate!
We can see the exact same teaching about the Sabbath in the description of Mary Magdalene going to the sepulchre Sunday morning.
Once again we see the language of one Sabbath being past (Saturday), and they came to the tomb early in the morning of the FIRST of the Sabbaths (Sunday). Very plain language that God is telling us a New Sabbath Day has begun. Again, in your translation one of the words may read "Week," but both of the words are the identical word, Sabbaths [sabbaton]. God is alerting us that the old testament Sabbath is past, and with the resurrection of Christ, it's the start of the FIRST of the Sabbaths. What some Theologians don't understand, is that God knows what He is doing, and has inspired to be said exactly what He wanted! He is not in the coincidence business, his word is inspired and every word deliberate, intentional, purposeful, and meaningful! Every jot and tittle.
With the rising of Christ came the end of work and began the FIRST of the New Testament Sabbaths (day of rest). And like all the ceremonial laws, with their fulfilment in Christ, the passed on. The Passover ended, and the Lord's supper was the Beginning of the New. As the sign of Circumcision was ended, and baptism was the Beginning of the new Sign of Salvation. The time of the High Priest ended, Christ was now our more perfect High Priest to make intercession. God gives us these spiritual pictures to show us that these Old Testament ceremonies and types were [skia] or shadows of what has now come. i.e., they were types pointing to Christ!
In fact, we can see this clearly as God deliberately Links the seventh day Sabbath right along with the Ceremonial laws that had ended with Christ.
..He that hath ears to hear, let him hear!