Those of us you are Christian sabbatarians believe He did precisely that, by the examples of His resurrection on the first day,
The case that he was resurrected on Saturday is much stronger biblically as Diego has pointed out numerous times.
His pouring out of the Holy Spirit on the first day,
The significance was that the outpouring of the spirit happened on Pentecost, one of God's Holy Days. This shows once again how important God's holy days are. They foretell and remind us of prophetic events in God's plan of salvation.
Most of these are suppositions to justify historical change. The fact is that Christians were keeping the true sabbath for quite a while after the death of Christ. In fact, it took an official edict from the Catholic church at the council of Laodecia in 360 AD to STOP Christians from observing the true sabbath:
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 [A.D. 360]
This is well over 300 years, 3 centuries AFTER the death of Christ.
Changing a commandment of God, one of the ten commandments, would be a huge controversy in the biblical church. Yet it is never, ever mentioned as an issue in the bible. Yet somehow it becomes an issue 3 centuries later?
{For old covenant sabbatarians, the painful fact remains that nowhere in the NT do we find the Jewish/gentile church worshipping on the last day sabbath of the Jews.)
Nonsense.
Act 13:42 And when the Jews were gone out of the synagogue, the Gentiles besought that these words might be preached to them the next sabbath.
Only gentiles are left. The gentiles want to be preached to, they want to go the church, the NEXT sabbath. They understood that the normative day of worship, the commanded day of worship by the God they wanted to worship, was the sabbath.
Act 13:43 Now when the congregation was broken up, many of the Jews and religious proselytes followed Paul and Barnabas: who, speaking to them, persuaded them to continue in the grace of God.
Act 13:44 And the next sabbath day came almost the whole city together to hear the word of God.
The whole city came to church to hear the word of God...on the sabbath, as God commanded, a holy convocation:
Lev 23:2 Speak unto the children of Israel, and say unto them, Concerning the feasts of the LORD, which ye shall proclaim to be holy convocations, even these are my feasts.
Lev 23:3 Six days shall work be done: but the seventh day is the sabbath of rest, ye shall do no work therein: it is the sabbath of the LORD in all your dwellings
Those who want to learn about God, convene on the day he said to convene on, the sabbath day. In Acts 13, if the whole city didn't come to hear about God on the sabbath, they didn't hear about God.
I know some folks like to slice and dice the Scriptures, so let's look at the entire context:
But when they departed from Perga, they came to Antioch in Pisidia, and went into the synagogue on the Sabbath day and sat down. And after the reading of the Law and the Prophets, the rulers of the synagogue sent to them, saying, "Men and brethren, if you have any word of exhortation for the people, say on." Then Paul stood up, and motioning with his hand said, "Men of Israel, and you who fear God, listen: ... So when the Jews went out of the synagogue, the Gentiles begged that these words might be preached to them the next Sabbath. Now when the congregation had broken up, many of the Jews and devout proselytes followed Paul and Barnabas, who, speaking to them, persuaded them to continue in the grace of God. On the next Sabbath almost the whole city came together to hear the word of God. But when the Jews saw the multitudes, they were filled with envy; and contradicting and blaspheming, they opposed the things spoken by Paul. (Act 13:14-16,42-45)As far as we can tell, this was not church. It was an apostate Jewish synagogue were Paul was preaching the gospel of salvation thorugh Jesus Christ, and where some gentiles came to hear his message.
Paul was preaching on the sabbath because that was the custom of the Jews. The gentiles came out to hear Paul on the sabbath because that was his customary day to preach to the apostate Jews.
This is the same sort of Jewish synagogue where Paul was often cast out of for his preaching of the good news of Jesus Christ. In fact in this context we also learn:
Now when the Gentiles heard this, they were glad and glorified the word of the Lord. And as many as had been appointed to eternal life believed. And the word of the Lord was being spread throughout all the region. But the Jews stirred up the devout and prominent women and the chief men of the city, raised up persecution against Paul and Barnabas, and expelled them from their region. (vv. 48-50)So to suggest that old covenantr sabbath day worship is being enjoined on the church by this sort of event is pure nonsense.
Old covenant sabbath day worship was always associated with the apostate Jewish synagogue, not the new covenant assembly.