As soon as practicable after the return day stated in the process, the examiner shall proceed to hear evidence and make up his final report to the court. However, if it has developed from the preliminary report filed by him that persons other than those named as defendants in the original petition are entitled to service or notice, the hearing shall not begin until after ten days from the date of the service of notice upon such persons. The examiner shall give notice of the time and place of the hearing to the petitioner and to persons who have filed any pleading in the case.