When to ask for a medical expertise?

Ideally, as soon as possible after the accident, in order to be advised by a independent medical expert, that you chose, in the procedure that will be setup and against the medical advisors from the adverse party (generally, insurance companies), that won’t miss to contact you rather quickly, and in a unilateral approach, after the traumatizing facts (traffic accident, work accident, medical accident… 

Also read: what is a medical expertise ?