I have never been exposed to epgy after you have been hitting the books for a while.
I am not sure what the K-7 includes. If you have time a Good Pre-Algebra course would be nice to get in before he started Algebra in 6th. Some say you don't need Pre-Algebra. Some say don't go without it. You could also supplement with previous AMC8 and AMC10 contest. You can also get previous MathCounts contest to take.