Carte Advantage eg Jeune, Senior, of various types are 50% off till 28th November. So 24,50 Euros for a 1-year pass instead of 49,00 Euros. Reductions on rail fares they give are prob 25-30% depending on the pass.
The offer is on SNCF Connect app and Trainline, probably other rail sales places too.
You can choose a start date up to 5 months ahead. Beware though as new rule in past year or two seems to require your pass to be valid on the date you use it to book a ticket, even if you’re booking for a later date when your pass would be valid.