(4) Fix a day for a preliminary hearing not less than two or more than three months from the date of the filing of the complaint; except that the hearing may be accelerated upon the application of the approved agency and upon notice to the plaintiff if the agency determines that removal of the child from the plaintiff's home is required, in which case the court shall appoint a guardian ad litem to represent the child at all future proceedings regarding the adoption.
Whenever the plaintiff is a stepparent of the child, the court, in its discretion, may dispense with the agency investigation and report and take direct evidence at the preliminary hearing of the facts and circumstances surrounding the filing of the complaint for adoption.
Whenever a plaintiff is a brother, sister, grandparent, aunt, uncle, or birth father of the child, the order may limit the investigation to an inquiry concerning the status of the parents of the child and an evaluation of the plaintiff. At least 10 days prior to the day fixed for the preliminary hearing the approved agency shall file its report with the court and serve a copy on the plaintiff; and