Julia has a not-so-subtle way of letting us know when she is done with her bottle.
She slaps the bottle away from her.
It's a big THWACK with her hand, and there is no doubt she is saying she is done.
She CAN hold her own bottle, however, she prefers kicking back in our laps, with her hands usually balled up into little fists, sucking it down as we hold it for her. Who can blame her, really?