The original D day was delayed by 24 hours due to bad weather.
Today's news coverage allows the public to remember what sacrifices people made 75 years ago, and I'd agree to declas today would be crass.
To go live after POTUS leaves Ireland at 09.30am GMT, would seem a way to do it. 24 hours after original D day.
That would be 04.30 EST, which I'm sure an Anon suggested from a proof analysis was whetho gs might get interesting