The guitar that I got him has nylon strings. I thought that would be critical too. I made that mistake when I got my wife a guitar years ago. I got her one that had a slim neck and light touch, but the steel strings bothered her.

I sat with my son over the weekend, and had him help with tuning the guitar. I tuned mine, then had him play the strings on mine while I tuned his. I tought him the names of each string. I figure if I just keep repeating that, he'll remember at some point. Then I asked him to tell me which note was higher while i was I was tuning. When we were tuned, i had him play a note on his guitar, and told him that I would try to play the same one on mine.
I really can't teach him chords yet. He needs to learn how to press the strings well enough to get notes.
Right now he insists on laying the guitar in his lap. He won't hold it against himself. (Makes it hard to play chords) I want him to just have fun and explore. I'm not going to push it.