Preschool is really for kids 3 and older. Before that, it's structured daycare! To be considered "preschool age" most schools will require that your child be 3, so you may want to consider having her start that January after her birthday.
Go visit different preschools and see what you like. What draws you to Montessori? Do you know what it's all about or is it something you have read about? Do some research and call around.
We visited 5 different preschools before selecting one for our son. I'm not a fan on Montessori, but those who like it love it. We visited a parochial preschool, private "prep" preschools, and a community-based preschool. There were things about each that we liked and disliked, but in the end decided on one of the "prep" preschools b/c that's where my son was visibly most comfortable. He had fun and didn't want to leave! The other "prep" preschool felt like a "learning lab" and the director wouldn't allow our son to touch the toys. Needless to say, HE asked to leave!
You'll know which one you like when you see it!