GE:
You can never separate love and truth just like you can never separate hate and untruth. The Seventh Day Sabbath of the LORD GOD is hated-- therefore so much untruth is spread around about it. Like yours, that "The early Church (1st Century) worshiped upon the first day of the week."
A LIE born of hate for truth, in this case GOD'S Sabbath's truth.
And Yes, God demands worship every day of one's life; and of the Church's life, God demands "SABBATHS", "... eating and drinking of Feast whether of (occasional) month's or of SABBATHS' " 'weekly' recurrence, "... CHRIST BEING THE SUBSTANCE of Feast ..." and "... NOURISHMENT ministered".
"DO NOT let anyone condemn you with regard to ..." it!
But, CORRUPTED the Sunday-lovers the Word of God's Love, and made it say the word of their hate, "Let nobody prescribe to you to keep the Sabbath!" NAB.
Sabbath given to isreal under the law, per Old Covenant...
Sunday NOT a Sabbath to Church, but recognised as day jesus rose from the dead!