We have debated for many a long year on JWN about the "proper" date for the Passover/Memorial and my conclusion is that JW's get it all wrong for a number of reasons, but as the Gospels are contradictory, nobody can say for sure.
Most years they are close to the time by a day or so, signalled by the Full Moon occurring about then.
I believe this year they have chosen Saturday April 11th.
This is a full week, near enough, away from the Full Moon.
What has gone on with their calculation ?