The leaked schedule indicated that the 50th anniversary special will premiere in the US at 2.45pm Eastern Time - and with the worldwide simulcast, the five hour difference seems to imply that The Day of the Doctor will be broadcast in the UK at 7.45pm on BBC One.
While the schedule has now been pulled - and the BBC won't be confirming the UK broadcast time until about ten days before the 23rd - it seems like a likely time, considering that the BBC will probably have to fit in Strictly Come Dancing on the same night.
The schedule also revealed a few other details of BBC America's 50th anniversary schedule - including the broadcast time of docu-drama An Adventure in Space and Time, which will be broadcast on Friday 22nd November at 9pm ET (the drama isn't expected to be simulcast with the UK), documentaries Explaining Doctor Who (which will be broadcast in the UK by Watch on 12th October) and Tales from the TARDIS, and a short 15-minute pre-show for The Day of the Doctor on the 23rd before the evening repeat at 7.15pm ET.
All of this is subject to change - especially The Day of the Doctor's broadcast time.
[Source: Doctor Who News]