I live in Colorado and was served with a summons along with a complaint. The complaint has not yet been filed with the court. I recently found this under Rule 303:
c) Time of Jurisdiction. The court shall have jurisdiction from (1) the filing of the complaint, or (2) the service of the summons and complaint; provided, however, if more than fifteen days elapses after service upon any defendant before the filing of the complaint, jurisdiction as to that defendant shall not attach by virtue of the service.