It is not when you start hearing Slade and Wizzard in November. It is not even when Tesco starts stocking Christmas puddings in October. You are way out.
Christmas for GPs actually starts in about April. That is when your eye drifts down the annual leave wallchart or spreadsheet and lands on the vast blank area at the bottom - the empty white snowscape of the second half of December.
Your eyes flit left and right to see if any of your partners have spotted it yet. It does not look like it. So you book Christmas off for yourself, right?
You don't want to be the Grinch who steals Christmas for everyone else (again).
Now there is just the staff party to go. No - not the turkey dinner, party hat and Shania Twain marathon at the hotel.
I mean the one on Christmas Eve in the practice with the Co-op orange juice and the crisps on paper plates.
Finally, things should quieten down - it's Christmas Eve, lunchtime, and the inverse care law is cruelly applied. If a couple of you nip off early the entire practice population of 7,000 will require emergency appointments, with the exception of those in residential homes who will require emergency visits.
If you all stay late it will be as quiet as the grave and you will end up fighting over the only scrip request.
I find the best technique is to turn off all the lights and stay below the windows playing Trivial Pursuit, then slam the door shut and bolt it the second the PCT phones go off at 3pm.
And then, for two blissful days, your time is your own to spend as you see fit.
Unless, that is, you're working a co-op shift in which case the humbug is kept in the cupboard behind the scotch.
Dr Richard Brown, GP35 panel member, Manchester.