FlyerTalk Evangelist
Join Date: Nov 2018
Location: Istanbul, Turkey
Programs: TK Elite Plus,BAEC GGL,ITA Executive, AFKL Gold,QR Gold,HH Diamond,Bonvoy Gold,ALL Gold
Posts: 14,186
They don't open US availability for Business Saver in advance as they know that people who prefer not to fly in Economy would pay for a paid-Business ticket. At least this is true for %90 of people who do not want fly Economy on a 10h+ flight. And most of these people buy their tickets in advance.
Availability generally opens 7-30 days before the flight. Believe me or not, I have helped a family member upgrade on the IST-LAX route, 4 days before departure via the website upgrade tool while there was no 'J' availability since the flight was booked until that day.