I don't think there is a standard " too soon " with some kids. It sounds like hes ready to at least dip his toes in and see what its about!
I was seriously thinking about letting DS8 do the EPGY math this summer after having it recommended to us after testing this past summer and since I'm constantly perplexed at the levels given in 4th grade (gifted) here (how long can a class focus on addition and subtraction, even if its in riddles its not any harder!) It sounds as though you and your son would recommend it.
Let us know what his teacher thinks will be good for his placement! Congrats to your son on his fabulous testing results!
