On Thursday, Ms Truss announced that the price cap would be held at £2,500 for two years instead of rising to £3,549 in October.
Greg Jackson, chief executive of Octopus Energy, said firms were still going through the detail of the new Government proposal but that customers should “sit tight and wait to hear from their energy supplier".
He added: “Nothing will change until 1 October and we'll be in touch with everyone before then.”
Scottish Power also said it would inform customers of the new change in their plan before September 19.
“What this does is it this buys us time,” chief executive of the company, Keith Anderson said.
Energy supplier, E.On has also said that customer do not need to do anything as it would implement the Government scheme across all tariffs.
Experts say Ms Truss’s scheme may cost up to £150billion but the prime minister has insisted the new plan was essential due to the current climate.
The Prime Minister's official spokesman said: "The public should be reassured that the energy price guarantee will be in place for households from October 1, as planned."
In order to help secure the UK’s energy supplies, Ms Truss has also issued new licences for oil and gas exploration in the North Sea, and has lifted the ban on fracking for shale gas.