Run the tap at the nearest sink to flush all the cold water from the pipe (between the hot water tank and the machine can be a long way so be patient).

Once the water comes out piping hot start the dishwasher.

Then avoid using hot water in the house for anything else that may use up all the hot water from the tank.

This is a perfect time to scrape/pre-rinse the dishes to make sure no large bits an especially no other dish detergents on the dishes.