(a) Objection may be made to the admission of a minor under Section 3-503 or 3-504. When an objection is made, the minor shall be discharged at the earliest appropriate time, not to exceed 15 days, excluding Saturdays, Sundays and holidays, unless the objection is withdrawn in writing or unless, within that time, a petition for review of the admission and 2 certificates are filed with the court.(b) The written objection shall be submitted to the facility director of the facility by an interested person 18 years of age or older on the minor's behalf or by the minor himself if he is 12 years of age or older. Each objection shall be noted in the minor's record.(c) The 2 certificates which accompany the petition shall be executed pursuant to Section 3-703. Each certificate shall be based upon a personal examination and shall specify that the minor has a mental illness or an emotional disturbance of such severity that hospitalization is necessary, that he can benefit from inpatient treatment, and that a less restrictive alternative is not appropriate. If the minor is 12 years of age or older the certificate shall state whether the minor was advised of his rights under Section 3-208.