I’m the same. Mad Sunday was always the first Sunday of June. The provisional dates I’ve seen are a week early, maybe that doesn’t apply anymore.
I did see the Senior Day bank holiday was on the 12th June next year, whether that’s right I don’t know, but in theory it’s correct.
Surely the dates are going to be released before D Day on the 19th. I believe vans can be booked online this year.