I'm not sure if you can buy a Eurail pass in Italy. You could ask Trentalia.

There are 2 ways to get your Eurail pass, one is to purchase a mobile pass online which is loaded onto a mobile phone and then freely and safely used on all trains operated by Trenitalia, albeit with some reservations needed.

There is also a paper pass which would be sent by mail (or possibly purchased at major stations in Italy). This offers the same access to trains as a mobile pass but you register each train in your paper pass as you travel (plus the same reservations).

Given you do not plan to travel until November you can buy your passes many months into the future, a mobile pass almost up to the time of your first train and a paper pass a few weeks ahead to ensure delivery, which can be a few weeks from ordering.

This would be the same for a Global Pass that covers all countries in Europe or the single country pass that only gives free travel within Italy.