Black Friday used to be a day of excessive shopping and deals for retailers taking advantage of consumers with Thanksgiving vacation time. But as the online and offline worlds merge, the distinction between Black Friday and Cyber Monday is quickly disappearing.

Retailers are stepping up their online offers for the weekend, but those who wait until Cyber Monday to lure customers are going to miss out on large returns.

Black Friday and Cyber Monday are seen as opportunity for retailers to fix lagging sales numbers and lure early holiday shoppers, but as retailers jump the gun on holiday deals, it can get harder to see the impact of set shopping days.

Simon Dumenco at AdAge writes:

“This year, marketers have particularly diluted the meaning of Black Friday, given all the pre-Black Friday, and “better-than-Black-Friday” deals they’ve been plugging ad nauseam.”

And yet, many consumers still organize their shopping around the date of Thanksgiving. Barclays Capital analyst Robert Drbul tells the Wall Street Journal that this weekend can be expected to generate 10% of total holiday season sales:

“It’s hard to play catch-up. A lot of what you are seeing (in terms of store promotions) is surgical and tactical. It’s well-planned.”

That said, the concept of Black Friday is more concrete than Cyber Monday.  U.S. consumers flock to stores on Black Friday because they have the day off and often spend that time shopping. But as online and offline shopping merge, they don’t have to wait until Monday to go to the office and use the internet.

Dumenco notes that Cyber Monday mentions on Twitter are a fraction of those for Black Friday:

Black Friday has been subsuming Cyber Monday for a while. ComScore reported last year that traffic to online retailers was up 98% over 2007’s Black Friday, and getting consumers out shopping during the entire weekend is much more important than arbitrarily pushing them toward deals targeted to next Monday.

Survey research from Google and OTX found that 32% of consumers plan to do most of their shopping during Thanksgiving weekend. Google found that searches for “Black Friday deals” started around two weeks earlier than last year. According to PayPal, its first major spike in online-payment volume occurred 16 November.

Meanwhile, price wars have broken it out weeks ahead and retailers like Amazon began Black Friday deals early this week.

“Web (retailers) have woken up,” Fiona Dias, executive vice president of strategy and marketing for GSI Commerce, tells the Wall Street Journal. “What Amazon.com has realized is that if they wait till Monday, consumers will be broke…For online retailers to wait until Cyber Monday, they are going to be out of the game.”

Images: top, Shoes.com. middle, AdAge, Trendrr.