puffin & chay's advice.

And expanding on some previous points: the WISC-V starts at age 6-0, the WPPSI-IV ends at age 7-7. During the overlap age bands, suspected high cognitive children should be tested on the WISC. All cognitive instruments require a 24 month waiting period between retests. Scores start to be considered relatively stable around age 8 or 9.

...pronounced like the long vowel and first letter of the alphabet...