This is a difficult question because we know very little for certain about the history of the period in which Homer was writing and we know very little about Homer.
The Trojan War, if it was an actual, historical war, took place around 1200 BCE. Homer, if there was an actual, historical person with this name, is thought to have set them in writing between 750 and 725 BCE. Thus, "Homer" may be describing a time period some 500 years before he lived.
On the other hand, we know much more about Vergil and the time period in which he lives. We know that he lived in Italy during the first century BCE. We know that he died in 19 BCE during the reign of the Emperor Augustus, who had restored order to the Roman world after two decades of civil war.
Thus, Aeneas' mythical arrival upon the shores of Italy is something that would have happened at least a thousand years before Vergil lived. Vergil inserts, however, numerous references to actual persons and events from actual Roman history into his epic, such as Augustus' victory over Antony and Cleopatra at the Battle of Actium, which is depicted on Aeneas' shield (Aeneid 8):
On the other side Antony, with barbarous wealth and strange weapons,
conqueror of eastern peoples and the Indian shores, bringing Egypt,
and the might of the Orient, with him, and furthest Bactria:
and his Egyptian consort follows him (the shame).
(A.S. Kline translation)
Vergil's epic is a literary one, whereas Homer's epic is an oral epic, passed down by word of mouth over hundreds of years.
As for the subject matter of the epics themselves, Homer's Iliad describes about a 45-day period during the tenth year of the Trojan War. Homer's Odyssey describes a ten-year period after the Trojan War. Similarly, it takes Aeneas seven years to travel from Troy to Italy.