The sooner the better.

Often, getting a lawyer when you first find out you are being investigated for a crime may be the smartest thing you do to fight your case, especially if the police or federal agents want to speak to you or you are subpoenaed to (or a target of) a grand jury.

Often, however, a client had no idea that they were being investigated until the police knock at their door. Even then, getting a lawyer immediately (or asking for one before talking to the police), is the smart thing to do.