No...I think Christmas Eve and afterwards will be a bad time. Maybe if you try it within the next two weeks or so - then he has plenty of time to get over it.

I would suggest telling him before Christmas. You might be surprised as to how helpful he could be. It would give you someone to talk to when you feel you're reaching the point of SI. I assume its worse when you have no one to talk about it with (for me at least). Then there isn't anyone to try to stop you...