If the Royal wedding is brodcasted live from London, then the ceremony which starts at 11a, in London will Air in North America at 6am. However, I believe that there will be a pre-wedding show, showing all of the guests or majority of the 1,900 guests that have been invited arriving to the Abby. I believe that will start at 9 or 10 am in London, which will turn out to be 4-5am in North America.
If we are not seeing a live viewing of the Royal wedding then it may start later on in the morning or even the afternoon.
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them