You have to send the petition to the cops and DA 60 days before you file a court action. Do it 60 days from the date on your letter. No one's going to complain about that.
You need to file the motion at the courthouse criminal department with an extra copy that they will either require you to serve on the DA or agree to do it for you. You will than be given a court date for you request to be heard. Start over with the court not the PD.
Hire a locally experienced criminal defense attorney to take over to make sure this is done correctly, and timely.
Law Offices of David Shapiro 3555 4th Avenue San Diego, CA 92103 (619) 295-3555