Shoppers have spread the cost of their Christmas food this year, according to Sainsbury’s.

The grocer, which like its counterparts expects this Friday to be the busiest day of the year, has observed that consumers began stocking up on holiday eats three months ago.

Sainsbury’s said that it had “noticed a trend this year in customers staggering their shop, with some spreading their shop across the days, weeks and months leading up to the big event”.

A third of customers bought mince pies and Christmas pudding “from as early as September to spread the cost of their Christmas treats”.

According to Sainsbury’s, December 23 will be “fizz Friday”, when half a million bottles of sparkling wine are expected to fly off the shelves – 25% of customers are anticipated to be planning to drink bubbly as part of their Christmas Day breakfast.

Christmas Eve is likely to be the biggest trading day for Sainsbury’s convenience stores, when Bucks Fizz and croissants are expected to be bestsellers.

Separately, value grocer Aldi expects to sell 11 million packs of vegetables this Christmas – double the volume of last year – as a result of selling such goods at 19p per pack.

Aldi joint managing director of corporate buying Tony Baines maintained that the grocer was successfully competing on quality as well as price.

He said that many Aldi products “are sourced from exactly the same suppliers as high-end retailers, but sold at unbeatably low prices”.