An infusion pump device and method for filling a fluidic system of the infusion pump with liquid medicament prior to infusion operation is presented. A control unit causes the infusion pump to: (a) bring a pump to an initial state; (b) switch a valve to a first state connecting a secondary reservoir to a first conduit and a primary reservoir; (c) retrieve medicament from the primary reservoir; (d) switch the valve to a second state connecting the secondary reservoir to a second downstream conduit; (e) expel the secondary reservoir contents into the second downstream conduit; (f) switch the valve to the first state; (g) retrieve the primary reservoir medicament; (h) switch the valve to the second state; and (i) expel the secondary reservoir contents into the second downstream conduit by shifting a piston to the initial position.