This paper focuses on the dynamics analysis from the ultra-short to the short period from a Post-Keynesian perspective. It is argued that the construction of both the short-run and the long-run models are based on the critical assumption of an equilibrium between aggregate demand and aggregate supply. Starting from the work by Metzler (1941. The nature and stability of inventory cycles, The Review of Economic Statistics, 113-29), the issue of equilibrium and stability is investigated inside a Keynesian-Kaleckian perspective. The suggested model analyses under which conditions the standard Kaleckian conclusions are still valid considering a disequilibrium situation. Two scenarios are simulated: one with fixed expectations as in Metzler (1941. The nature and stability of inventory cycles, The Review of Economic Statistics, 113-29) and another based on adaptive expectations and asymmetric behaviour of the wages-unemployment relation. The model questions the effective demand labour curve and suggests that an increase in real autonomous expenditures, mainly by the government, might be even more essential than what is generally considered in the Kaleckian literature, to avoid increasing unemployment a world with increasing wages.