NEW YORK — Saturday afternoon was, for most New Yorkers, just another shopping day — the 14th in the frenetic countdown till Christmas. But for Joseph Carter there was a more pressing deadline: only 96 hours left till the Marc Jacobs holiday party.

In his Chinatown apartment, Carter, the women’s wear design director at the company, is putting together his costume for the annual soiree. Already two weeks in the making, it’s a period piece that caters perfectly to the evening’s theme: The Red & Gold Masked Ball.

“I wanted to be a big bird at first,” he confesses, “but then I thought of the colors and of a masquerade ball, which led to the 18th century and to Marie Antoinette.”

Oui, by Tuesday night this mustachioed man, who last year won the party’s best costume prize for his Coco Chanel getup, will become the Princess of Versailles.

“I love the process,” Carter says. “The appeal is in the learning, the making of it, the sewing.”

He has turned his living room into an atelier. A pannier, nine-feet wide, sits on a mannequin, while bolts of red and gold fabric are strewn left and right. Eric Pettigrew, Carter’s boyfriend, pieces together masks from miscellaneous odds and ends: tassels, Indian “dandiya” sticks and Shirley Temple curls, while the costumer himself is crouched over on the floor, sewing the dress on his lap. “Dangerous Liaisons” is, naturellement, playing on a television set in the background.

“Joseph’s effort on his costume is like his effort in work — it’s flawless,” says Jacobs. And no detail is overlooked. To wit: A makeup-artist friend is scheduled to arrive Saturday evening for a trial run and Carter has booked a delivery van to transport him to the party. Marie Antoinette does not make for hasty cab hailings.

“It’s just a costume party,” Pettigrew has to remind his boyfriend when Carter calls Pettigrew’s shoes “lumpy,” the by-product of too many layers of protective tape.

At her apartment on Roosevelt Island, Doina Iftode, a trim buyer for the company, is having a countdown of her own. Of the nine costumes on her list to make, Iftode has only completed one: a beribboned, shiny red frock for Leslie Clements, vice president of sales. At the top of her list is Robert Duffy, Jacobs’ longtime business partner, but the Swarovski crystals she needs to glue on his pants won’t be arriving until the next day. She also has an Empress Josephine, a Renaissance pageboy and her own Little Red Riding Hood trappings to complete. Monday will have to be a personal day off.