Just to make sure I understand the question, you want to know the timescale that the original audience of the plays would have perceived as the era during which the action of the play takes place? If so, while Herodotus is not the only relevant author, you might find it useful to peek at 2.145 from his History:

"Among the Greeks, Heracles, Dionysus, and Pan are held to be the youngest of the gods. But in Egypt, Pan is the most ancient of these and is one of the eight gods who are said to be the earliest of all; Heracles belongs to the second dynasty (that of the so-called twelve gods); and Dionysus to the third, which came after the twelve. How many years there were between Heracles and the reign of Amasis, I have already shown; Pan is said to be earlier still; the years between Dionysus and Amasis are the fewest, and they are reckoned by the Egyptians at fifteen thousand. The Egyptians claim to be sure of all this, since they have reckoned the years and chronicled them in writing. Now the Dionysus who was called the son of Semele, daughter of Cadmus, was about sixteen hundred years before my time, and Heracles son of Alcmene about nine hundred years; and Pan the son of Penelope (for according to the Greeks Penelope and Hermes were the parents of Pan) was about eight hundred years before me, and thus of a later date than the Trojan war." Herodotus was writing in essentially the same timescale as the Antigone, so he places the Trojan War between 900 and 800 years before his time (Heracles is supposed to have sacked Troy before the Trojan War, and the bow he passed to Philoctetes becomes part of the Trojan War story, so it gives us a good start date which the war must have come after).