A medical device comprising an infusion device comprising a fluid reservoir to contain a therapeutic fluid and a transcutaneous access tool fluidly coupled to the fluid reservoir, the transcutaneous access tool configured to deliver the therapeutic fluid subcutaneously to a patient； wherein the infusion device operates in a stand-by mode prior to the therapeutic fluid being introduced into the fluid reservoir； wherein the infusion device operates to deploy the transcutaneous access tool within a predetermined deployment time period upon filling the fluid reservoir to a predetermined fill level with the therapeutic fluid.
