It depends on how the matter was ultimately resolved.
Under the current law (which may not be in effect for very much longer now the CORI reform bill was passed on July 31st) if you were CONVICTED of the crime you were arrested for, you would either have to wait 10 years (for a misdemeanor) or 15 years (for a felony) before you could petition the Commissioner of Probation to seal the record. CORI reform has reduced these waiting periods to 5 and 10 years, respectively.
If you were not convicted, i.e. the matter was dismissed, nolle prosse'd, no probable cause was found, no true bill was issued by the grand jury, or you were found not guilty, you could petition the court immediately to seal the record, although the judge considering your petition will have discretion to deny your petition if he/she feels you have not met your burden of proof.
Sealing your CORI is something better done with the help of an experienced attorney.