I was around 9 years old before I had been in a church which was on Sunday. For 55+ years since I attended Sunday (first day) churches. That was also our the rest day for my family.
A few years ago my wife and I decided to visit a Saturday (7th day) Baptist church. We liked it and have attended that church since. I have, for a long time, had some concerns about Sabbath keeping as to whether it was important or not. I have come to believe that it is the best day to keep, though God seemed to honor my commitment to Sunday worship keeping and though most of the evangelization around the world has been done by Sunday worshippers.
Jesus, in the Olivet Discourse prophecy in Matthew 24, Mark 13 and I believe Luke 21, when prophesying the destruction of Jerusalem including the temple admonished the Christians to pray that the day come not on the Sabbath day. He was inferring that the Sabbath would still be in effect a number of decades after Penticost when the Christian era officially began. Jesus and the apostles also usually went to the temple on the Sabbath to minister.
The Genesis record says God rested on the 7th day. That's not Sunday but Saturday. If there were not a Sat church that I liked in my area or a Sunday one I liked much better, I'd go back to attending Sunday church but would retain Saturday (7th) as my rest day.
Having said the above, I judge nobody for whatever day they keep or whether or not they keep one. The apostle Paul said we should not judge anyone as to what they eat or drink or concerning the Sabbath day. He went on to say that one keeps one day and the other another and that if you keep it, you keep it unto God and if you keep it not, you keep it not unto God. He also said some regard one day and others regard all days alike. See Romans 14
BUZSAW B 4 U 2 C Y BUZ SAW ---- Jesus said, "When these things begin to come to pass, then look up, and lift up your heads, for your redemption draws near." Luke 21:28