There were numerous “sabbath days” but only on Sabbath. The Jews, apostles and Jesus kept Gods law. That was consistent. There were manmade rituals and laws that they did not observe because they did not apply.
Set aside one day a week for worship and you will be fine, doesn’t matter which days, when you argue this stuff you will find that whole denominations are built on this one premise. I have no problem with a group worshiping on Saturday or Sunday as long as you or obedient to God’s Word.
The exact day would be something that would be important to Pharisees.
Jesus didn't think much of Pharisees.