To expunge an arrest, investigation, or detention with police (basically police records), you must (1) wait 30 days from any arrest, (2) there must be no criminal case pending, and (3) charges were not filed or the statute of limitations expired.
To expunge a case dismissed with prejudice, you can immediately apply.
To expunge a case dismissed without prejudice, you must wait 180 days since the day of dismissal or have the prosecutor consent in writing to issuing a certificate of eligibility.
To expunge an acquittal, you can immediately apply.