Afaik, the first Antifa were a coalition of left wing groups in Italy fighting fascists in the 1920s. They didn’t necessarily use the term but they were the first active anti-fascists so that counts in my book 🤷
As a side note, they were left to fight both the fascists and the royalists alone, since the Italian Liberals refused to get involved until it was clear who would win and then joined the fascists.