Activating Eurail pass in Lesce- Bled Train Station

My adult son is flying from the USA into Ljubljana, Slovenia airport and will take a shuttle to meet me in Lake Bled in June. We are leaving the next day (a Sunday) to go to Hallstatt, Austria via a few train stops. He has a Global Eurail pass, but this will be his first opportunity to activate it. It says in the Eurail instructions that a pass can be activated in any train station. Will he be able to activate this pass in Lesce-Bled when we get to the station? Will the ticket window be open and will there be someone to activate it? Our train leaves at 10:03. How early should we be in the train station? Will the ticket window or office be open at that time? Should we consider trying to go there on the Saturday he gets to Bled at about 16:00? Will we have enough time to go on Saturday before the ticket window closes? We would probably have to take a taxi. I have no idea what kind of hours the ticket windows are open. Thank you!