Twentieth year

Then he went straight into the house and among the proud suitors, but the fate of black death took Argos when he had seen Odysseus in the twentieth year.

Odyssey Book 19 line 193-195 Barry B Powell
Odyssey Book 19 line 295-297 Barry B Powell

Artemis goddess of the moon by Guercino

So, it is completely plausible that the War and Odysseus' return took no more than 19 plus years. Which fits the cycle of Meton perfectly and moreover the rite of Apollo.

This is something that isn't much discussed in literature, but it fits perfectly all of what Homer described so far.

As Apollo's Day being a family day like Christmas, it is to be expected that a lot of people returned home like Odysseus. Like we still do allover the world every year.

It is also plausible that Odysseus' trick with the Troyan Horse can be set on November 22nd too. It would have been completely logical for the Troyans to belief they all set of for home that day. Spending a month to sail home and leaving behind the Troyan Hors as a tribute to their invincibility.

Well, we know how that ended.
Let's return to Odysseus and Penelope and see what more is discussed.

'The Stranger' tells Penelope that he had seen Odysseus on his way to Troy and she asks him what kind of clothes he was wearing.

The twentieth year, that is between 19 and 20 years ago. The duration of the War at Troy and Odysseus return is a shorter period than 20 years, unlike the 20 years were scholars always are writing about. Odysseus must have left Ithaca after Telemachos was born and before Telemachos' first Apollo Day.

Woman, it is hard for one who was been so long gone to speak of this. It is already the twentieth year since he went off and left my country, but I will tell you as I remember it.

This is not the only time Homer mentions the Twentieth Year. Right on the moment he entered the palace, when his dog Argos did recognize him.