One of the things that I've always liked about WW is that this concept is sort of built in through having daily points but also having weekly points that you can arrange as you like them. I use most of the ones I use on the weekend. On my calorie counting website (livestrong) I keep track of the weekly calories I've eaten in addition to the daily calories so I make sure I am still in a calorie deficit.
All of that said, as you get closer to goal there is much less room for error. My DH is within 10 pounds of his goal now and doesn't lose at all if he eats too much on the weekends when before he would lose.

I might have a glass of wine with dinner too. Depends. I'm looking at this as a lifestlye and how I'm going to eat forever, I have to learn it or I'll just end up gaining it back, that's what I've done in the past. For instance my partner and her hockey team she coaches had their Christmas dinner at a chinese buffet this week. I stocked up on veggies, very little fried rice and sushi, fruit and a little rice pudding for dessert. I spurlged a bit but the key is not to over stuff and watch your portion size. I've been doing this every weekend since I started my journey in June