“And after eight days again his disciples were within, and Thomas with them: then came Jesus, the doors being shut, and stood in the midst, and said, Peace be unto you.”
King James Version (KJV)
20:26 After eight days - On the next Sunday.
Joh 20:26 After eight days again his disciples were within, etc. It was on the second Sunday after the resurrection; the second Lord's day in the history of the world.