I think around here I've always seen between 4 and 7 as 'the window' for the epi.
For me, natural childbirth is just how it is done. It's a concept that I was raised on. Literally, when I was way too young to understand anything else about my body as a female, I knew it was for growing and nursing a baby. I saw my first live birth when I was 5 -- I was taking care of my upstairs neighbors son, because her best friend was across the hall giving birth, which is where my mother was as well. I knew there was hollering involved.

My mother was a La Leche League Leader (international organization dedicated to support of breastfeeding) and a Lamaze teacher.
I've had people tell me, 'oh, you just don't know, you'll change your mind'. (Real nice thing to say to someone who is desperate for a baby, right?) But I tell people it would be like me, at 29, suddenly deciding that I will walk on my hands instead of on my feet. To me, it's how my body works.