It is generally recommended to run hot water before starting the dishwasher. Running hot water helps ensure that the dishwasher starts with hot water right away, which can improve the efficiency and effectiveness of the wash cycle. The hot water helps to dissolve detergent and remove food particles more effectively, resulting in cleaner dishes. It also aids in activating the dishwasher's heating element, which is responsible for raising the water temperature during the wash cycle.
Running the hot water at the sink closest to the dishwasher for a minute or two before starting the dishwasher helps to purge any cold water from the pipes and ensure a hot water supply. This practice ensures that the dishwasher is using hot water from the beginning and doesn't waste time and energy heating up cold water.
However, it's worth noting that some modern dishwashers have a built-in heating element that can heat the water to the required temperature, even if the water supply is initially cold. In such cases, pre-rinsing with hot water may not be necessary, but it is still a good practice to ensure optimal performance and energy efficiency. Checking the dishwasher's user manual or consulting the manufacturer's guidelines can provide specific recommendations for your particular model.