You're correct that Kiera hasn't arrived at the tavern yet, but I'm sure they've met - if Varrick is 24 and arrived to live with Brand when he was 9, that means Kiera was 19 when Varrick came. Kiera left when she was 24, and if Varrick left Brand when he was 17, that means they have a living-with-Brand overlap of five years, making Varrick 14 when Kiera left. :3