Consumers heading out for their 'big shop' ahead of the Christmas break could lead to one of the biggest ever trading days for UK supermarkets.

Sainsbury's expects today (Friday) to be the best trading day in its history, with predictions of a £160m spend by customers online and in store and an online grocery order set to be delivered every second through the day between 7am and 11pm.

Meanwhile Waitrose is anticipating 11am to 12pm today will be the busiest hour of the festive season at its tills. A vehicle is scheduled to leave one of the supermarket's distribution centres every 90 seconds and more than 5,000 temporary staff have been brought on board to help over the period.

Tesco is braced for more than 20 million people to shop in its stores over Friday and Saturday – and expects to serve 15,000 customers every minute.

Its branches are stocked to sell 200,000 turkey crowns and birds today alone, as well as 27 million carrots and 60 million British Brussels sprouts.

Kantar Worldpanel estimates UK shoppers will spend a record £4.2bn on food and drink in the final week before Christmas, with today seeing the biggest single day of sales.

Sainsbury's chief executive Mike Coupe said: 'We know it's going to be a bumper shopping weekend. Over 1,800 colleagues from our central offices will be in stores over the next couple of days, helping everyone stock up ahead of the big day.'

Meanwhile, Morrisons is taking steps to ensure customers remember often-forgotten items ahead of most supermarkets closing at 4pm on Christmas Eve in accordance with Sunday trading rules.

The items include batteries for toys, tin foil, sticky tape, cranberry sauce, napkins, biscuits for cheese, pigs in blankets, brandy butter, bread sauce and stuffing.

Checkouts are being redesigned so that shoppers trail past the items, in-store radio messages will be used to jog customers' memories, and checkout managers will wear uniforms which list the items on their back.

Last year, 320,000 shoppers visited Morrisons after 4pm on December 24.

Retail analysts ShopperTrak expect high street footfall to rise 37% on the daily average on Friday as consumers fit in last-minute shopping around the last working day before Christmas.