A method for forming and filling a container with liquid. The container being formed from a preform located within a mold and the method utilizing a hydraulic blow molding device that is coupled to a source of the liquid, which is used as the blow molding medium. The hydraulic blow molding device has a blow nozzle and a member that is extended from a retracted position to a position within the preform. A blow nozzle engages in fluid tight communication with an open end of the preform so as to provide a sealing engagement of the blow nozzle with the preform. The liquid blow medium is injected into the preform so as to form the container after sealing engagement of the blow nozzle with the preform. The member initiates its advancement into the preform prior to the time of sealing engagement of the blow nozzle with the preform.