My son was coasting and still scored top 1-2% on MAPS in 4K, K, and 1st. (He was the only 4K student to take MAPS, it's not routinely done in 4K). Toward the end of 1st grade he dropped in some areas to 3%, which is not alarming, but was one piece of evidence showing that he wasn't thriving in ANY way in public school.
I used to care very much, and maybe a few years ago I might have suggested some prep, but now.... no, I definitely do not recommend prepping for standardized testing. The gifted program is not a guarantee he will be challenged in school, nor that he would apply himself. I wish the answers were simple and clear "get into this district, this program and everything is going to be okay". Heck, I'd move to Nevada for the Davidson school if it was that straightforward.
Your son's benefit, or lack of, from any academic program rests more on his non-academic abilities than his academic abilities, IMO. His social skill, motor skills, executive functioning skills, leadership, self-advocacy, work ethic, resilience are hard to measure, but can make or break a school experience. Put your energy towards these things, because acceleration/enrichment/extension without the child possessing soft skills will cause disappointment.
