I started around 36 ..by 38 weeks (had GD) I was induced for the first .
my second I dilated around the same time and had him naturally by 38 weeks.
third baby so we'll see if she will come like her brothers did. hopefully
It all depends on the person some people start really early but normally you should start at around 36-37 weeks unless your dr had reason to suspect your dilating he won't check you until then