How long do you have to report an accident to your insurance company and what happens if you don't report it if no other vehicle is involved?

my son bimmed a lady in a theater parking lot she took his phone number but never called it has been approximately 2 months and she called and asked him his information today can she still fill a claimYour policy contract says you must 'promptly' report all accidents, however I must say that while they can/may deny a claim for late report in twenty plus years I've only seen this twice. Report the claim immediately.