Today and then tomorrow and that's it. Time is up.

Presumably the things that needed to be mailed have long since been wrapped and deposited at the post office, a supply of batteries (not included) has been laid in, the tree is up, the pudding down from its shelf. Nothing left to do except realize that you have forgotten to buy a gift for the host or hostess who will give you Christmas dinner.

Depending on exactly how many times you've put your feet under that particular table without saying a proper thank you, it can be an extravagant wicker picnic basket from Brooks Brothers (1840 L St. NW), with sandwich boxes, silverware, thermoses and blue and white china ($140 for a basket that serves two, $185 for four or $250 for six), or a box of Christmas candles accompanied by a set of eight candle fitters ($2.25) from Brookstone, 1140 Connecticut Ave. NW. The little rubber circles that keep candles from wobbling in their holder may not be a very extravagant gift, but they're a practical one.

A hunt board or a tour of England's stately homes is too expensive, but you could pander to the current Anglophilia with a set of four placemats showing hunting scenes from the English countryside ($68 at Brooks Brothers.)

If all you can afford is peanuts, buy some -- 10 lbs. for $10, properly roasted and stuffed into a burlap sack at Preferred Stock, 3301 New Mexico Ave. NW. Or, if Christmas hasn't entirely emptied your pockets, present 4 lbs. of similarly packaged pistachios at $40.

Has experience with this particular host taught you that the holiday meal will be a gourmet delight? Then wrap up the new game Gourmet Challenge, a sort of Trivial Pursuit for the person who lives to eat. See if your host knows "What does the term sur lie mean?" and if all you get is a blank look, show off by explaining it is "On its lees." Well, all right, that refers to the sediment that settles in wine during fermentation. See. The holidays can be educational. The game is $45 at Cherishables, 1608 20th St. NW, which also has lengths of absolutely beautiful lace that could be used to make a tablecloth. One pattern is $14 a yard; the other, imported from England, $24.

Chestnuts roasting on an open fire are traditional to the season, and though you'll have to get the chestnuts at the supermarket, The Kitchen Bazaar (4455 Connecticut Ave. NW, Seven Corners Shopping Center and Montgomery Mall in Bethesda) has the pan to roast them in for $11.99. They also have a copy of Penelope Casas' book, Tapas (Knopf, $12.95), which will help the up-to-date hostess cater to the new craze to graze. Keeping to the Christmas colors, there is a red and white checked apron ($16), and the thoughtful guest would not only give it but would wear it after dinner, while cleaning up.

Still in the holiday colors are the cocktail napkins in varying patterns of red and green at the Herb Cottage at the Washington Cathedral, Wisconsin and Massachusetts. A set of six is $7.15. Down the lane from the Herb Cottage is the Cathedral Greenhouse, which is crowded with red, pink and white poinsettias. Small plants are selling for $2.95, bigger ones, $5.95, bigger still, $8.95 and biggest -- well it varies.

Williams-Sonoma, 5300 Wisconsin Ave. NW, has Christmas crackers to put a bit of snap into the holiday; a box of 12 is $12.

Another possibility is an assortment of homemade preserves. Even if you didn't get around to putting up the fruits of summer, Homespun (966-6695) did. There is a cranberry chutney and a plum conserve, each a perfect accompaniment to a holiday meal ($7 for a 12 oz. jar.)

No one wants strenuous exercise after Christmas dinner, but what could be gentler, or more potentially rewarding, than taking turns batting at a pin ata and scrambling for the scattered gifts when someone finally hits? The Paper Store has a Santa Claus, a reindeer or a snowman for $11.50 each and what you put in it is up to you.

Or celebrate the way they do in Italy, with a holiday offering of Pannettoni (the 1 lb. cake is $4.95; 2 lbs., $8.95; 3 lbs. $12.95) or a 2 lb. tin of Amaretti cookies ($25) from A. Litteri's, 517 Morse NE.

You could also visit the German Deli, 1331 H St. NW, and make your contribution to the feast some good luck symbols for the holiday season -- a marzipan pig for $2.35, or a chocolate horseshoe, $1.20. And if you're afraid your host may decide to forego the fruit course, provide it yourself with a collection of marzipan fruits.