" so the JW's are a full 24 hours early in their observance."
I pointed this out to a JW lady I knew well many years ago, she was one who insisted the Org. was right about everything.
When I had proved your point to her, she flounced off, throwing over her shoulder the comment "I don't care if we celebrate it on the wrong day", !!???
But I guess that will be the attitude of J.W's today, sadly, they really do not care about Truth, which is ironic in the extreme, the way they bandy that word around.