Quick! You have 25 days to get the kids in shape to make a good presentation at Christmas dinner. Like a lot of stuff in parenting, consistency and patience are by-words and yes, you can teach a toddler new tricks. Here are the basic etiquette skills little ones should have: 
- “Please,” “Thank you” and “You’re welcome” are not optional. Repeat them over, invite your kids to correct you, and you’ll find by Christmas a pleasant and polite Pavlovian response.
- Eating with fingers is for babies, with the obvious exceptions (pizza, ribs, chicken legs for example). Little kids can use a fork, though you may have to help load it up from time to time. Resist the temptation to feed them and they will pick up this skill, leaving you free to get them another glass of milk.
- Kids need to ask to be excused to leave the table. Teaching kids not to run around during dinner is not easy, but you’ll make it harder if you chase them around to get them to eat.
- Salt and pepper go together. Pass them together for a polished impression.
- Even little kids can and should use napkins, keep them on their laps, and learn to use them rather than wiping their hands on their pants.
You can make it easier for the kids by eating dinner in a room without distractions like TV, and make a rule not to allow toys or books while eating the family meal together.
Good luck and Bon appetit!