Welcome!
The MAP test shows he is high-achieving. He may also be gifted. There are lists of
traits, but an IQ test provides the definitive answer.
what can we do to challenge him
Parents can often provide academic/intellectual challenge at home. Parents can also check their
State laws and school policies to see what ideas those resources offer. Parents can
advocate for specific changes to their child's curriculum, placement, pacing, learning environment.
At what age should a parent administer an IQ test and what is the best test?
The ideal age may be 8, unless there is a need to test earlier. The test(s) may depend upon the
test administrator. The latest test is the WISC-V.
If the IQ tests come back gifted, then what do we do?
If the scores are high enough, apply to the
DYS program.
Any recommendations for a supplemental at-home math curriculum?
Like everything else, that depends on the child. Have you looked at Art of Problem Solving, Beast Academy?
Are there any online games/tutorials to challenge him? I’d like to give him something to do for a half hour to an hour a day, math strategy games and puzzles preferred.
There are several sources of free online Sudoku games.
LOL, SaturnFan, we posted 16 seconds apart... and included some of the same information for the OP! 
