Will this be the year when Black Friday is finally dethroned from being the biggest shopping day of the year?

Bill Martin thinks so. The founder of ShopperTrak, a Chicago-based firm that measures store traffic, has become a guru of sorts when it comes to predicting and measuring the ebbs and flow of the holiday season.

According to ShopperTrak, Black Friday has reigned as king of the holiday shopping season – and of the entire year for that matter — every year in the last decade by bringing in the most sales on that day. But its supremacy has begun to wane as more stores have begun opening on Thanksgiving night.

Macy's has already said it will open at 6 p.m. on Thanksgiving this year. Other major retailers have not yet announced their hours for that day, but Martin expects that more will follow suit.

"Our numbers show over the last three years that Thursday sales are growing at a pretty rapid pace," he said. "It's leeching sales from Black Friday."

Instead, he expects Dec. 20, the last Saturday before Christmas, often referred to as Super Saturday, to be the No. 1 shopping day this year in terms of sales.

Black Friday should still slide in at the No. 2 spot, he said, followed by the day after Christmas, which falls on a Friday when many people should be off from work. His firm, by the way tracks in-store traffic and purchases, and does not include online sales in its forecasts.

He added that the Thanksgiving night openings are not leading to an overall bump in sales. They are just taking away sales from Black Friday.

"Retailers say that consumers are clamoring for them to be open on Thanksgiving, but that's not the case," he said. "They're just attempting to get to the wallet before the money is gone. That's what this holiday creep is all about."

Martin was in town this week for the Shopper Marketing Conference & Expo held at the Minneapolis Convention Center.

So how robust will the holiday shopping season be this year? His firm will finalize its forecast in the next week or so, but he said he is expecting it to be in the range of 2.5 to 3.5 percent for in-store sales. That is a bit lower than the National Retail Federation, which has put out a rosy forecast of 4.1 percent increase for holiday sales. Martin added that he thinks the NRF's number is a little optimistic.

"Growth is slowing a little bit, but growth continues to prevail," he added.

Also, he said to expect to see retailers being more aggressive in November with promotions. It's part of a decade-long shift to more holiday sales that month as retailers try to get the shoppers' wallet earlier, he said.

"November continues to grow as December declines," he said. "That stroke of midnight after Halloween, you're going to start seeing the Christmas promotions."

Get ready for it.