Madrid, Toledo, Seville, Granada, Barcelona, San Sebastian, fly out of Bilbao. First, and probably only, trip to Spain. Trying to book train either from Granada to Barcelona or Barcelona to San Sebastian. Will fly one of those. Can't book a ticket. Am I too soon, too late, or too inept?
I just tried booking a ticket for Jan 16 and couldn’t but I can on Jan 15: https://www.renfe.com/es/en.
You are way too early. Usually it's 3-4 months out to buy tickets.