How do books 1-4 of The Odyssey prepare us for the introduction of the hero Odysseus in Book 5?
Like all good epics, Homer's The Odyssey starts in media res, and so we come to the story in the middle of things. As such, we don't get to directly meet our hero, the wayward and wandering Odysseus, until Book 5. Homer uses this narrative to set the stage for Odysseus' future heroism.
Homer establishes context in a few ways. First, he describes the degradation of Odysseus' home in Ithaca. By outlining the extent of the suitors' depravity and the oppression of Penelope and Telemachus, Homer clearly signals the decay of a king-less Ithaca. As such, we are well aware that Odysseus is needed, which in turn makes us more anxious to finally meet the man.
Additionally, throughout these books we hear vague and mysterious snippets of conversations regarding Odysseus. Whether we're hearing the gods arguing about him on Mt. Olympus, or listening to Menelaus discuss his potential whereabouts, we're constantly hearing about the king of Ithaca without actually meeting him. In this way, we are able to establish vague inklings of the lost king's fate, although we're never able to say for sure what he's up to. This also increases our anxiety for meeting the king, and it only makes it that much more exciting when we actually meet him well into the poem during Book 5.