Per Illinois Supreme Court Rule 505, you should follow the instructions on the back of your ticket if you intend to plead "not guilty" to the charge.
TO AVOID MULTIPLE COURT APPEARANCES:
For non must-appear tickets: If you intend to plead "not guilty" to this charge, and if, in addition, you intend to demand a trial by jury, notify the Clerk of the Court at least 10 days (excluding Saturdays, Sundays or holidays) before the date set for your appearance. A new appearance date will be set, and arrangements will be made to have the arresting officer present on that new date. Failure to notify the clerk of either your intention to plead "not guilty" or your intention to demand a jury trial may result in your having to return to court, if you plead "not guilty" on the date originally set for your court appearance. Mail or bring the blue copy of your ticket to the Circuit Clerk's office BEFORE the court date listed on the bottom of your ticket. DO NOT APPEAR IN COURT on the date listed on your ticket. A new trial date will be mailed to you. If you appear in court on the date listed at the bottom of your ticket, you may still plead "not guilty" before the Judge, but your trial will not be heard that day. A new trial date will be scheduled.
For must-appear tickets: You must appear in court on the date listed on your ticket. If you wish to plead "not guilty", a trial date will be set and arragements will be made to have the arresting officer present on that new date.