The pre-Christmas sales bonanza - previously a 24-hour affair that has become the UK's biggest shopping day - has seen most major retailers start their Black Friday deals almost two weeks early with deals on everything from electric toothbrushes to holidays abroad.
They are promising new deals on Friday and many are extending their opening hours, including Tesco opening the "majority" of its Extra stores early at 5am and John Lewis closing some of its stores later than usual.
Experts have pointed to the evolving nature of the event, which has progressed from brawls over cut-price televisions to last year's "muted" high street turnout, with many predicting increased spending online this year.
Retailers will be hoping for an improved performance from their websites, many of which struggled to cope with the volume of traffic last year.
John Lewis, whose Black Friday offers last year translated into its biggest week for sales in its 150-year history, said it had prepared for a smooth online experience for shoppers and an "atmosphere of calm" in stores.
John Lewis operations director Dino Rocos said: "Additional staff will be on hand across our 48 shops to ensure the high levels of service our customers expect is maintained."
British shoppers are expected to spend £2.3m a minute this Black Friday - a 19% increase on last year - despite warnings that they should "ignore the hype" and exercise caution.
Some 14 million British consumers are expected to participate in the global shopping event, now the biggest shopping day in the UK, and will spend a predicted total of £1.96bn, according to VoucherCodes.co.uk and the Centre for Retail Research.
Online spending on Black Friday is expected to reach £1bn, up 16% on last year, while it is anticipated that the majority who opt for the High Street will spend a lower total of around £961m.
Well over half of online sales, 59%, are set to be made via a mobile device, accounting for £591m of total spending.
A survey for BHS.com found 21% of shoppers planned to spend more this year than last year, and just 9% intended to spend less.
Kevin Jenkins, UK and Ireland managing director at Visa, said: "Looking at the spending patterns last year, Black Friday shifted online in a big way.
"Spending was predominantly spread across the four days between Black Friday and Cyber Monday.
"With major retailers focusing more on online and mobile channels this year, as well as launching promotions from as early as last week, the shape of Black Friday spend is likely to evolve from last year."
Consumer group Which? has already warned shoppers to "do your research" after finding that half of last year's deals were cheaper in the months before and after Black Friday.
John Willcock, head of credit cards at Post Office Money, said: "Many people feel that retailers are extending the Christmas sales season to be longer than ever before, in an effort to get people in-store and shopping online, leading some to feel a certain element of 'discount fatigue'.
"However, our research shows that shopping events such as Black Friday and Cyber Monday are still very popular as people try to offset Christmas expenses."
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