US March 24, 2015
EU March 25, 2015
JP March 26, 2015
UK March 27, 2015
Wat in the F
CoD releases on a Tuesday over here, tons of stuff does (many Friday however). I guess it's something to do with weekly charts or some irrelevant BS like that. IIRC it's insanely unusual for EU and UK to release at different days.
edit: 28GB I've seen quite a lot, sounds legit. Might be just about doable on my connection. Thing I'm most worried about is not being able to pause it when I actually want to play online and having to suffer terrible ping. All depends if it's a proper download (which you can pause) or one of those background downloads which you cannot.