Pre-1945 arrivals, 1945-1955 arrivals, 1956-1986 arrivals, and post-1986 arrivals. My husband's family were all pre-1945. I am a post-1986 arrival myself.
After looking at time, in other words, dates, I look at space - geographical origins.
Italy is even more regional than Britain, and for that matter, Australia. Someone from the Veneto is likely to find a person from a peasant background in Calabria completely incomprehensible in conversation!
I spent much of the first half of my life in various parts of England, Wales and Scotland. I know, from first-hand experience, the difficulties regional languages and dialects, and unfamiliar accents and phrases, can cause.
Mass multicultural migration has been a post-1945 phenomenon in Australia. I put it into three categories because of the influence of television in people's lives. In Italy, most people did not have access to television until the mid 1950s.