Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Development of Alphabets in Italy
Not less important for history than the derivation of the alphabet is the further course of its development on Italian soil: perhaps it is even of more importance; for by means of it a gleam of light is thrown upon the inland commerce of Italy, which is involved in far greater darkness than the commerce with foreigners on its coasts. In the earliest epoch of Etruscan writing, when the alphabet was used without material alteration as it had been introduced, its use appears to have been restricted to the Etruscans on the Po and in what is now Tuscany.
In course of time this alphabet, manifestly diffusing itself from Atria and Spina, reached southward along the east coast as far as the Abruzzi, northward to the Veneti and subsequently even to the Celts at the foot of, among, and indeed beyond the Alps, so that its last offshoots reached as far as the Tyrol and Styria.
The more recent epoch starts with a reform of the alphabet, the chief features of which were the introduction of writing in broken-off lines, the suppression of the -"o", which was no longer distinguished in pronunciation from the -"u", and the introduction of a new letter -"f" for which the alphabet as received by them had no corresponding sign. This reform evidently arose among the western Etruscans, and while it did not find reception beyond the Apennines, became naturalized among all the Sabellian tribes, and especially among the Umbrians.
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Reference address : https://www.ellopos.net/elpenor/rome/1-14-measuring-writing.asp?pg=22