(a) Date for Hearing. The date for the adjudicatory hearing shall be set at the earliest practicable date but no later than 40 days from the filing of the petition unless otherwise delayed by order of the court, which order shall set forth the reasons for the delay. Failure to schedule the adjudicatory hearing within the prescribed 40 day period shall not operate as a ground for dismissal except upon an affirmative showing of material prejudice. (b) Notice of Hearing. Notice of the adjudicatory hearing shall be served on both parents and both shall be ordered to be present, and if the child is not living with the parents, the guardians or persons with whom the child resides. The parent or guardian shall be required to be present and not excused from attendance except by the judge upon a showing of sickness or other justifiable cause.