The general rule is to wait for about 48 hours after your window replacement before you can do a DIY car wash. The reason for this is that the replacement procedure most often includes attaching the windshield with an adhesive substance, which needs to dry in order to keep tight and strong. If you want to be 100% safe and sure that you do not harm your newly replaced car windows in any way, it is best to wait 2 weeks until you do any public car wash as the adhesive takes that amount of time to fully dry.
In case you want to do the washing on your own, you can do so in 4 to 5 days, because you no longer put the pressure of machinery and brushes on your vehicle. The idea is to avoid any type of direct pressure on your windshield. Thus, you should do the washing gently, by using a wet/damp cloth and making sure you do not aim the hose at the windshield.
Rain does not affect newly replaced windows, because it is sparse and does not carry the same force as the water from a hose would. By taking the necessary precautions, you can make sure your car remains intact during the washing process. Front Range Windshield Pros is a professional windshield replacement company that does a superb job.