When did the Odysseus's adventure with the Cyclops happen?
Odysseus narrates the story of his dealings with Polyphemus, the Cyclops, in Book IX of The Odyssey. Odysseus is speaking to King Alcinous of Phaeacia, telling him and his family the story of where he has been since the end of the Trojan War. In his telling of this history, when his crew left Troy, they first landed in Ismarus, and -- long story short -- they partied a little too hard, got very drunk, and they were attacked by the Ciconians. His men fought hard, but six from every ship were lost.
After this, they drifted for many days and eventually found themselves in the land of the Lotus-eaters. There, being cautious, Odysseus sent only three men to investigate the inhabitants of this land, and when they tasted the lotus flower offered to them by the natives, they no longer wanted to go home. Odysseus had to drag them back to the ship.
Next, after their experience with the Lotus-eaters, his crew landed on the island of the Cyclopes, and it was then that Odysseus and his men have their run in with Polyphemus, the Cyclops and son of Poseidon.