I know "they" say to start transitioning to a sippy at 12 months, but Riley drinks from a cup so you've got that down.
 
We're now just starting to really try with the sippy, but honestly she seems to hate it (though maybe that's one thing that we'll have to wait and see on with her corrected 1st birthday).
 
Ahhhhhh wait and see not a concept I'm good at :P