A medicament delivery device has a drive mechanism that includes a first resilient member and a delay plunger rod assembly that includes a proximal plunger, a distal plunger, a chamber formed between the proximal and the distal plungers, an aperture, and a delay device in the chamber. The distal plunger is positioned and configured in relation to a hold and release mechanism such that, as the drive mechanism exerts a pressure on the medicament container, the distal plunger acts against the delay device, delaying a release of a signal generating member after a release of the drive mechanism to allow remaining contents of medicament in a medicament container to be completely expelled before the signal generating member is released.