What is the best way to start potty training????

my 20 month old is fallowing me to the bathroom like she wants to learn but she doesn't really know what the toilet is for yet i don't know whether to start training her or just leave her for a but because she isn't even 2 yet, but she knows how to put her diaper on and know how to put her toilet seat on the big toilet and get up on to it like she wants to go but she doesn't know when she has to go. so if i'm confused then she is confused so i don't know how to go about this.....anyone have any stories that might help me get a good grasp on how to get her to start going potty on the potty. help?