As far as I'm concern sex ex starts when you give birth.
Start with teaching the proper names for body parts and that touching them yourself is okay, but it's not okay for other people to touch you there.
I taught my girls where babies came from, when their sisters were born. Lessons were simple, but I always let them know that their father supplied a wiggly little sperm that with the egg that was inside me, made the baby.
My oldest was 5 when the youngest was born and I used a book that show each stage of the pregnancy to show her how the baby was growing inside me.
By Second grade he was explaining how you could and could not get AIDS to her fellow classmates and I was proud of her.
Sunday, my daughter and I both told my grandson that he should never feel guilty about ************* Seems he mention that he had seen **** to an adult who was a feminist and she one of these **** is violence types,so he was feeling guilty about it. We told him that not all **** was bad and ************ is healthy and normal.
We were rather **** with the woman who tried to make him feel guilty.