Were the Apostles and early NT church breaking the 2nd & 4th commandment by meeting on the Lord’s day, i.e. the first day of the week? In Acts we see:

Jn 20:19 Then the same day at evening, being the first day of the week, when the doors were shut where the disciples were assembled for fear of the Jews, came Jesus and stood in the midst, and saith unto them, Peace be unto you.

This word, ‘assembled’ is the same word used to describe the OT synagogue:

4863. συνάγω sunagō; from 4862 and 71; to lead together, i.e. bring together, hence come together (pass.), entertain:—assemble(1), assembled(5), came together(1), convened(1), gather(10), gather … together(2), gather together(1), gathered(9), gathered … together(3), gathered together(14), gathered … together(1), gathering(3), gathering together(1), invite(2), invited(1), met(2), store(2).

Robert L. Thomas, New American Standard Hebrew-Aramaic and Greek Dictionaries : Updated Edition (Anaheim: Foundation Publications, Inc., 1998).

see also: Matt 28:12, Matt 26:57, Matt 26:3

This word, ‘synagogue’ denotes an organized gathering. Keep in mind, all of these people were devout Jews who were highly familiar with the commandments and rituals. If the change of day did not come directly from Christ, we would see some obvious backlash in these early stages, and we don’t. Also, notice it says that Christ ‘stood in the midst of them’.

This verb: ἵστημι.

Contents: A. ἵστημι in Greek-Hellenistic Usage. B. Theological Aspects in the Old Testament. C. Judaism: 1. Sirach; 2. Philo; 3. Qumran. D. ἵστημι in the New Testament: I. Employment corresponding to General Usage; II. Theological Aspects of New Testament Usage.

ἵστημι is one of the verbs which take their sense from the relations in which they stand. It also involves the place where a person is set or stands and the question of what endures in the flux of time with its changes.

Gerhard Kittel, Geoffrey W. Bromiley, and Gerhard Friedrich, eds., Theological Dictionary of the New Testament (Grand Rapids, MI: Eerdmans, 1964–), 638.

In the midst of this ‘standing’ Christ validates the change by telling them all, ‘Peace be with you’. Would Christ be telling them ‘peace be with you’ if they were breaking the 2nd and 4th commandments? If so, this attributes sin to Christ! In fact, He tells them ‘peace be with you’ twice in the same passage, amplifying the idea and placing His royal stamp upon it!

Christ ‘standing’ shows that He accepts the change. Consider the lamp stands (or candle sticks) in the book of Revelation that denote a true church of God:

12 And I turned to see the voice that spake with me. And being turned, I saw seven golden candlesticks; 13 And in the midst of the seven candlesticks one like unto the Son of man, clothed with a garment down to the foot, and girt about the paps with a golden girdle.

The Holy Bible: King James Version, Electronic Edition of the 1900 Authorized Version. (Bellingham, WA: Logos Research Systems, Inc., 2009), Re 1:12–13.

The candle stick denotes truth. It denotes light. Christ is the light. He is a flame. He is sinless. Here we see the same language used of Christ, ‘in the midst’. Same word used in the last chapter of John. For John to write that they were gathered as the ‘synagogue’ of God says much; to deny it says that Christ was sinning as he obviously advocates for the change.