• Cards should go in the mail by week's end.
• Presents that must ship should begin their journey by the end of the week to make sure that they will arrive by Christmas Eve.
• You'll want to finish the bulk of your shopping this week. For the next two weekends, stores will be mobbed.
• Pick a day (or days) for baking. Perhaps while others are standing in line at the mall and post office, you can use the 22nd and 23rd to bake at home.
• Take some time to decorate the house. Make notes in your Christmas notebook about any decorations that will need to be replaced. Those are things you can look for during the after-Christmas sales.
• Continue gift-wrapping as time allows.
• Finalize menus for Christmas Eve, Christmas, New Year's Eve, and New Year's Day, especially if you will be entertaining guests. Make sure that you have all the utensils, glassware, plates, napkins, etc. that you need.
• Continue purchasing the non-perishables you will need for baking, parties, and holiday meals. 
• Take a few minutes to note the end date for the special grocery sales. I've noticed that many of the sales end after Christmas or even New Year's. That means that I can wait until after the holiday to restock my shelves with baking and cooking basics. Those sale items can get me through the winter. (What's better on a snowy day than a mug of hot cocoa and some freshly baked cookies?)

Holiday events (school programs, office parties, etc.) pick up this week.  That's why most of this week's tasks are finishing things you started in past weeks.  If you've been keeping up, next week will be smooth sailing!