induction

what's the best time to ask for/about getting an induction. my doctor said my baby is going to be too big for vaginal birth because I have such a small frame and that she was going to push a c section. id rather try and do a vaginal,birth before he gets even bigger. she said hes healthy, breathing, strong ect so if he were born today it would be fine. I just dont know how to bring it up.