Pushing the holding of the pen or pencil correctly was something I was always a bit unsure of when teaching my girls. I wondered whether it was something that came automatically over time anyway as our motor skills develop. After all, I don't recall being shown myself when I was learning to write, so did I reach that point on my own, or did I just not remember being shown? In my experience, some children just can't hold it correctly straight away and need to position it a little differently until their control has developed a bit more. So I'd demonstrate it, but not push it too much and the miracle that is child learning and development got them to the same point in the end.

By the way, I love your approach to keep things interesting for him by mixing things up.