How long should I wait before washing a newly ceramic-coated car with soap?

Follow the coating manufacturer's instructions, because the waiting period differs between products. Many coatings have two separate early-care periods: a shorter one during which the car should stay dry, and a longer one before shampoos or other chemicals are used. Nasiol coatings, for instance, specify 24 hours away from water and 48 hours before detergent-based washing. During that time, rinse off light dust or bird droppings gently with clean water if needed and dry with a soft towel. Avoid automatic washes, strong pre-washes and decontamination products until the coating has fully cured.