Pretty much when coinage was invented.
It allowed you to hoard wealth much more effectively. But it also subjected you to all the effects of increasing and decreasing currency supply and currency value.
Even so, in a barter society it is still possible for booms and busts. Consider:
When a new animal with superior fur is first discovered, that fur is so precious that only the village headman has status enough to own it. Some enterprising villager then decides to devote an entire season to finding where this fur can be found, and acquiring it to trade for necessities and luxuries, and to enhance his status. Sadly, when he returns to the village he finds that many of the other hunters had the same idea and the pelts are quite common now. No one wants to trade for his pelts.