I'm sure that statistically so very little alcohol gets into your milk that it's not worth worrying about, especially with the amounts you mention drinking. I happily feed DS who's coming up for nine months, after a couple of glasses of wine!
What you suggest sounds fine to me (it will be my first bfing Christmas too!). Key thing to remember is - if you'd be ok to drive then you're ok to bf.
As for timing, Kellymom says alcohol peaks in blood (and breastmilk) 0.5 - 1 hours after you've had the drink, but even this is a bit hit and miss as you sound more like a sipper than a downer to me! I would just drink as you plan to, feed on demand and enjoy the day!
I do like the suggestion on the other thread though that you could have a drink after every feed if they're a couple of hours apart and STILL no alcohol would go through to the baby Enjoy Christmas with your baby.