User blog comment:Lia Schiffer/416: Deicide 18 (The End)/@comment-3005023-20100818220700

Gin himself states that it took him many decades to finally learn the secrets of Kyoka Suigetsu, which would place that well after the events in TBTP. If I was Gin, I would not want to attack someone as dangerous as Aizen without some sort of plan to counter his abilities.