When do doctors decide on a C-Section for a breech baby?

At my 34 week appt a sonogram was done and my baby is breech. I am now 36 weeks and have an appt this week. I'm fairly sure the baby is still head up, I have not felt her turn around and I'm still feeling most of the movement down low. They have told me they will not preform the version thing because it is my first child, and I wont allow that to be done anyways. My question is, how many weeks will my midwife wait until planning to have a C-Section? And what week do they normally do it on?