For me, I'll do some shopping with my Mum (I'm nice like that), come home, have a little sleep (I'm selfish like that) and then put on An Unearthly Child at 5:15pm. After it's over at 5:40, I'll wait for the big one. And then watch The Day Of The Doctor.
Christmas Day (I like forward planning) - I'll put on about 8:00 The Name Of The Doctor, followed by The Day Of The Doctor and to complete the day, the regeneration special. Three hours of bliss to compliment what I did 20 years ago, when I sat through Planet Of The Daleks in one sitting (it had been repeated earlier in the year).