A system and method to automatically initiate an injection procedure of a medicament into a patient. In the system, a delivery assembly includes an injector for infusing the medicament into the patient. Further, the system includes a monitor for detecting a parameter characteristic of the procedure, for instance, a pressure indicative of a partial vacuum between the injector and the injection site, a pressure exerted by the patient against the delivery assembly, a conductance, a capacitance, or an optical blood reading. Also, the system includes a timer for determining compliance of the parameter within a predetermined range during a first time interval. In response to the timer, an actuator initiates the injection procedure at the expiration of the first time interval. Further, the actuator may stop the injection procedure if the parameter is outside the predetermined range during a second time interval.