Missouri Revised Statutes Title XXXVI. Statutory Actions and Torts § 534.070. Complaint and summons--court date assigned, when

1. When complaint to the circuit court of the proper county shall be made in writing, signed by the party aggrieved, his agent or attorney, and sworn to, specifying the lands, tenements or other possessions so forcibly entered and detained, or unlawfully detained, and by whom and when done, it shall be the duty of the clerk of the court to issue a summons directed to the sheriff or proper officer of the county, commanding him to summon the person against whom the complaint shall have been made to appear, at a day in such summons to be specified.

2. A court date shall be assigned at the time the summons is issued. The court date shall be for a day certain which is not more than twenty-one business days from the date the summons is issued unless, at the time the case is filed, the plaintiff or plaintiff's attorney consents in writing to a later date.