If you wash your car manually, there is no time restriction. You can wash your car immediately! However, it is best to avoid using direct water pressure, like a hose, when you rinse the soap from the windshield. If you use a hose, make sure to use low pressure on the windshield.
If you want to go to an automatic car wash, you’ll need to wait 24 hours. Since it takes time for the sealant to cure, the direct water pressure from the car wash can damage it. It also can put unnecessary stress on your new windshield.