How long should I wait?

well being raped is an awful thing that could happen, and is not her fault. Shes probably still in shock and shaken up but this. You need to give her support at this moment of time and let her know that you will protect her and be there for her. It will obviously be a long time until shes back to her normal self. If you love her, let her know this as she will feel more cared for and protected. Don't give up on her as this ordeal was not her fault, she just needs to know that shes loved and needs time to get herself back onto her feet.