When did Rome’s first period of expansion begin

Rome’s First Period of Expansion began in 509 B.C.E. when the Romans drove the last Etruscan king out of power.

The first period of large scale expansion was the first phase of Rome’s conquest of Italy in the interwar years between the 2nd ad 3rd Samnite Wars (304-298 BC) and the 3rd of these wars (298-290 BC). In the former Rome forced the Sabellic peoples of central Italy into alliances. By the end of the latter, Rome had taken control of and had alliances in the whole of central Italy, except from Etruria, and the present day regions Campania and Lucania in the south.
There was expansion, though far more limited than this, under the kingdom. This was in old Latium, the area around Rome. At the beginning of the republic (which begun in 509 BC) Rome had to defend herself against the attacks from Sabines, Aequi, and Volsci. It was not until the 380s BC that they became expansionist again by taking the Pomptine region, an area in the south of today’s Lazio. There was expansion from the Pomptine to Naples from the first to the second Samnite wars (343–304 BC).