Thanksgiving now a Black Friday 'prequel'? Big deals begin Thursday.

Thanksgiving diners apparently can’t drop their drumsticks and go shopping fast enough to please US retailers.

Many merchants are bringing Black Friday – the unofficial start to the holiday shopping season – forward to Thursday night. The early start is expected to increase weekend sales, a relief for retailers faced with yearly declines in consumer spending and other signs of continued economic distress.

“This is the fourth holiday season with recessionary factors still looming in the background … which means [retailers are] pushing promotions and consumer excitement and interest as early as they possibly can,” says Laura Gurski, director of global retail practice at A.T. Kearney, a global consulting firm based in Chicago.

Despite the front-loading of store hours, the traditional Black Friday will continue to dominate sales – 66 percent of this weekend’s likely shoppers say they plan to shop that day compared with 17 percent expected to start Thursday, according to a survey conducted by the international consulting firm Deloitte.

Among the retailers opening their stores late Thursday are Toys “R” Us (9 p.m.), Walmart (10 p.m.), Target (midnight), Kohl’s (midnight) Best Buy (midnight) and Macy’s (midnight). The Mall of America, in Bloomington, Minn., is also opening at midnight, the earliest in its 19-year history. The mall, the largest in the US, reports that it typically attracts 300,000 people on Black Friday.

To lure shoppers to this Black Friday “prequel,” retailers are offering a variety of incentives, including deals on limited-quantity items. For example, Toys “R” Us is promoting 50 percent discounts for shoppers who show up between 9 p.m. Thursday and 1 p.m. Friday. Similarly, Walmart is heavily discounting items for shoppers exclusively for its earliest Thursday night shoppers.

Best Buy is encouraging midnight shoppers to arrive early by announcing it will show “Harry Potter and the Deathly Hallows Part 2” outside its stores at 9 p.m.

Ms. Gurski says much of the allure around Black Friday has “a lot to do with the mystery and the thrill of the hunt.”

“The reason why consumers queue up or leave Thanksgiving dinner early is to get a special toy or item they have to have, and the price is irresistible, and they know [the retailer] is going to run out,” she says.

The early promotion is expected to pay off: The National Retail Federation estimates that 152 million people will shop on Black Friday, a 10 percent increase from last year. According to MasterCard Advisors SpendingPulse, Friday sales may clear the $20 billion threshold for the first time; last year US shoppers spent a total of $19.3 billion.

Deloitte reports that shoppers expect to spend an average of $224 this weekend.

“Strategically, retailers are moving things up as a result of the demand,” says Ramesh Swamy, a retail specialist with Deloitte. “Everyone is trying to race to the front now.”

The accessibility of online retailing is making Black Friday less essential for holiday shoppers, which is why the real unofficial holiday season is being pushed back as early as the first of November, Gurski says.

However, Black Friday may remain important simply because of tradition: Most shoppers do not have to work and, for those who use the day to shop, the enjoyment of the holiday lights and bustling traffic is important to enjoying the season.

“Our schedules are our schedules, so [Black Friday] gives an opportunity for the average shopper to get out there and get a jump on Christmas,” she says.