potty training a girl

i am thinking about when will be the "right" time to potty train A. any ideas? i'd like to have her trained by the time numero tres makes the debut june 5th. She would nearly be 2.5. B was waaaay trained by then. I guess I expect the same with her. He was really easy to train. A however, is so hard headed and strong willed. So, anyone out there that is reading this if you have some awesome tips for training a girl, send those tips my way! Hopefully it won't be too painful on us all.