De acordo com o Man in Seat 61, os trens estão à venda na Espanha 60 dias antes da partida. No entanto aqui ele diz:
The opening of reservations can be delayed for dates after the twice-yearly timetable change in June and December, as they're always late loading the data. The 60/90 days isn't exact, indeed, I often find that Renfe loads trains as and when it feels like it, often less than 60 days and sometimes certain trains appear on the system before others. If you don't see the complete train service which you are expecting to see, and it's over a month to go before departure, the chances are that not all trains have been loaded yet.
Então, o melhor é ser paciente. Suas páginas em Portugal confirmam a informação.