There are many approaches to this. I was very strict during my weight loss phase. But if you choose carefully, you can have a traditional holiday fare and still stay on plan.
If you plan ahead, and count calories and other nutrients, you'll do just fine. Check this link for how to calculate this. Post #5 and #6 are the methods I'd use.
Another approach is to eat whatever you want and worry about it the next day. I don't recommend that approach, because it is likely to lead to, "but there are leftovers, so I'll just continue to blow it for one more day." And then the neighbors invite you over, and they have a bunch of good food, so you decide one MORE day won't hurt. And pretty soon, you have pigged out the entire time between Thanksgiving and New Years, and you have a bunch more weight to lose instead of having continued to lose 4-8 more pounds.
So my recommendation is to not let the holidays be an excuse to make unhealthy food choices. Stick with NS most of the time. Allow yourself PLANNED specials meals that aren't NS food, but are still healthy stuff in proper portions.
Below is an idea of things you could use for Thanksgiving or Christmas dinner. The portion sizes are a suggestion, and the calories are averages that may not match what you cook or are served. If you use this list, remember that the combined total of the max calorie NS dinner, the max calorie NS dessert, the max calorie for a SmartCarb, and 2 servings of veggies, your count would be 650 calories. The total count of all the stuff below is 873 calories. So you can't eat the whole list, so pick and choose your favorites. Or go hog wild and have it all, and get right back on program the next day.
Turkey (white meat) 3 oz, Approx. Calories 133
Mashed potatoes 1/4 cup , Approx. Calories 75
Stuffing 1/4 cup, Approx. Calories 90
Gravy 1/4 cup, Approx. Calories 25
Sweet potatoes 1/4 cup , Approx. Calories 100
Green Beans (steamed) 1 cup , Approx. Calories 40
Cranberry sauce 2 Tbsp., Approx. Calories 40
Roll (no butter) 1, Approx. Calories 90
Pumpkin Pie (no whip) 1/8 of an 8" pie, Approx. Calories 190
Wine 4 oz., Approx. Calories 90