There is no definite answer to this question, however the sooner the better after potential misconduct is discovered.  When a company has knowledge of alleged impropriety, it is best for the company to get out in front of the investigation and to conduct its own complete and thorough investigation.  In many cases, if a corporate investigation is conducted properly, a governmental agency will rely on the findings of the internal corporate investigation.  When conducting an internal corporate investigation, it is always best to develop a plan that protects the attorney client privilege of the company. Based on the results of the internal investigation, the company will be in a better place to determine its next course of action, including the possibility of self-disclosure, settlement, or taking the position that the company did not do anything wrong.

Failing to act could turn an otherwise isolated incident into civil or criminal consequences for those who learned of what was occurring and did nothing.