I know Jehovah’s Witnesses keep the early Christian practice of celebration of the Lord’s Supper once a year, rather than more frequently as is the custom in other churches.
https://en.wikipedia.org/wiki/Quartodecimanism
But I wonder if others have come across anything about the JW practice of holding the Lord’s Evening Meal after sundown on Nisan 14, rather than say in the morning, or daytime, as many churches hold communion. Does this go back to the first Christians too?