RCS - how early b/c of very thin uterus?

Under.the.Rose

I was told by my midwives that the OB doing my RCS likely won't want me to go into labour because she noted that my uterus was very thinned out during my c-section with DS (he's not even 15 mths old now). 

I'm just wondering if that means the RCS would typically be 2 weeks before my due date? Or would they let me go longer? Experiences?