I found with Katie that independent play mostly came on its own (around 16 months, she generally wanted to play with us before that) -- more when she became more mobile and was happy wandering away and coming back and checking in on me. That being said, if you want to encourage her to play more independently, you could always busy yourself with something (folding laundry, reading) while she's in the room with you so she knows you're there and take breaks to play with her here and there. Generally with Katie, she'll play by herself for a bit and then bring me a book or toy or something to play with her and then wander away again. Later in the day she needs more one-on-one time, but she's always been pretty cranky later in the day.