How do you know when to start?

My DD is going to be 14 months this month and right now when she has to go she will squat and poop wherever she is and then if I ask her if she made poopies she will grab her diaper. Then we will say ok lets change your diaper and she will go up the stairs to her room. She still has wet diapers at night, but was wondering if I should slowly start introducing it to her. She is my first child so I don't have a clue how this works or how to even do it.

Any advice?