The simple answer is that it's a bit of a moving target. I've spent 30 years doing HIV prevention research in various communities from South Africa to inner cities. I've done large-scale research in inner cities where kids start wanting to have babies at 13 1/2, and obviously you calibrate education before that.
So partly it's a moving target. I would strongly suggest there's no such thing as sex education poisoning. There is no way of robbing a kid of their innocence. They'll simply tune right out. I think there is developmentally appropriate education, and it involves the sort of thing that I think Ontario is phasing in, with correct body-naming, respect for boundaries, good touch bad touch, and things like that. I think it can be effective, and I think it needs to be directed in a very specific and grade-appropriate way.
One other thing: Back in the distant past, I was able to assist with a study of about half the practising sex educators in the state of Indiana, and we found that the curriculum didn't make a bit of difference. What mattered was the teacher's comfort with the topic. So we've got to provide not only curricula, but we also have to invest heavily in staff selection and support and training. It's not fair to teachers to dump a curriculum guide on them.
The key point is let us all join in a direct attack on the unwanted potential effects of pornography. Let us all join in a direct assault on inequitable, coercive, and unhealthy behaviour, and cut to the chase.