I had a planned C-Section with my second pregnancy, my D.R planned it for 2 weeks ahead, so that would have made me 38 weeks, I think it might just be up to you and your doctor, Mind you I had a C-Section with my first baby but this was not planned.
My DH's Cousin will always have to have planned c-section and the baby will have to be delivered by 36 weeks she can never go into labor due to having helpps with her 1st baby and loosing that baby at 22 weeks. emergency c-section and a T cut in her uterus. Shes now pregnant with her 2nd (3rd) and due in May but baby will be here in early April.
Mine was planned because I had gestational diabetes and they were concerned my son would get too big. However, 3 weeks before his due date, I had issues where they ended up doing an emergency c-section. He was 8 lbs. 13.8 oz. 3 weeks early!