After an accident that is your fault, how long until you are contacted by insurance?

Last Thursday I rear ended someone in Boston. My car is mostly fine, but there was some damage to the bumper (mostly scratches) and a small imprint of my license plate in the bumper as well. We exchanged insurance information, but I am not sure if they are going to file the accident. How long does it usually take for your insurance company to call you? Am I in the clear after a week?