Heracles and the Titans' Quest for the Sky

Prometheus told Heracles that he would find the mighty Atlas, with the weight of the world on his shoulders. Most of the other Titans had been banished to a place called Tartarus for all eternity but Zeus obviously had special plans for Atlas and his brother. After explaining his quest, suggested that they make a deal. I will hold the heavens for you if you bring back three apples. This way, I don't have to steal from my stepmother or find my sister, and you get a much needed break. But Prometheus never specified how long this break was supposed to last.