Despite a severely short window, some retailers are still pushing free shipping offers to attract procrastinators. Saks, Neiman Marcus and L Brands' Victoria's Secret are offering free express shipping to online shoppers, while Amazon is offering a free 30-day trial of its Prime service. Customers who sign up for the trial can receive free two-day shipping on orders placed as late as midnight Sunday.
(Read more: Web sales on a billion-dollar hot streak)
Beemer at America's Research Group said all the 11th-hour promotions reflect customer habits. While Black Friday deals catch the early birds, sales in the last few days before Christmas cater to procrastinators. And with one less weekend between Thanksgiving and Christmas this year, many shoppers are under the gun.
According to the National Retail Federation, as of Dec. 9, 32 million people had not even started their holiday shopping.
Because of the weak start, Beemer said, smart retailers would be offering 60 percent to 70 percent discounts to get shoppers in the door on such a crucial weekend. But that probably won't happen, he added.
"They're going to gamble," Beemer said. "They're going to try to keep margins intact as best they can."
The same likely will not hold true after Christmas, though, as they try to boost their December numbers with even more drastic discounts, he said.
Experian data indicate that emails offering discounts of half off or more are likely to peak during after-Christmas sales.
And Beemer said that consumers will see "50 percent off, plus an extra 10 percent off 'this week only.' "
—By CNBC's Krystina Gustafson. Follow her on Twitter