Auntie Beeb's hand was forced by the release of a version from Latin America to unveil their trailer for The Day of the Doctor some ten hours early.
There are very few differences between this and what you most likely watched last night. It all comes down to text on the screen, in one way or another.
Meanwhile, it's been announced – at least on a banner on the BBC America YouTube channel – that the international simulcast of 50th anniversary programming will start at 2.50pm EST on November 23rd.
I expect something like five or ten minutes of introduction and fuss before The Day of the Doctor and then some kind of cool down or pundit discussion panel to follow after, likely tailored specifically to your TV market.
UPDATE: I have now checked with the BBC Media centre – the show itself will kick off at 2.50pm EST, or 7.50pm in the UK, and run for 75 minutes.