He really doesn’t have to “progress academically” at his age. Let him be a kid. He’s going there to socialize and play, not get ready for the SAT. It will be far more beneficial to him to be the older member of his class as opposed to the too young member of class for the next 13 years. Try a different Pre-K if this one is a problem but there is no benefit in rushing him and possibly actual detriment.