Npower has speculated that householders have been turning on the heating for short periods because they are experiencing a "faux winter", which feels colder than it really is because England has enjoyed such a hot summer.
Figures show September has only been marginally cooler - by 0.25C - than the same time last year, but gas usage is 15% higher, according to the company.
It predicts that demand will drop again at the end of the week, with the real "big switch on" likely to take place in the last weekend of October when households succumb to the winter chill.
Npower spokesman Patrick Purcell said: "What we're seeing is people turning their heating on for short blasts for an extra bit of comfort, as night-time temperatures drop.
"Looking at previous years, the weather forecast and listening to what our customers are saying, we wouldn't expect to see the big switch on until mid to late October."
According to its research, the evening of Saturday October 26 will see 60% of households switch over to regular central heating.
Npower's managing director of energy services, Simon Stacey, said: "We've had such an amazing summer, but because it's been so good with hot, sunny weather for months, now that it's dropped off a little people think it's colder than it really is.
"We understand that winter is an expensive time for our customers and there are some simple ways to get ready for now, before the real cold weather sets in."
The company recommends that households prepare for winter by fitting draught-proofing around windows and doors, ensure the loft has at least 11 inches of insulation and set the heating to come on just before getting up and switch off after going to bed.
It recommends that when very cold, households should turn the heating on earlier and off later rather than turning up the thermostat.
:: YouGov surveyed 1,037 adults online on September 16-17.