User blog comment:ChishioKunrin/Volume 6 Bingo/@comment-33287020-20180807231521/@comment-26018514-20180808031624

Isn't 2 impossible from what we know already though? If Spring's disappearance was the last great maiden crisis before Amber was ambushed, then the other maidens would all need to be older than ~ 10 years ago... and tbh if they were at that young of an age that they had just replaced one wouldn't you expect them to still be training?

Which would then mean realistically we are talking around 20+ years old to keep the Ozluminati unconcerned... but when they also seemed to define Amber as the youngest, it seems more likely even older than that.

so ~10+ at the youngest, with a skew towards something >20+sounding more likely.