finn has always been a little piglet and started feeding himself around 7 months. it might have been a little sooner than that, but i know it wasn't any later.
the first things we put on his tray for him to feed himself were the gerber puffs. he'd been on stage 3 foods for a bit though and those are very chunky and textured.
all babies are different. i'm sure she'll get it soon! finn went from playing with them but showing no interest in putting them in his mouth, to shoveling them in!