For a child who has been grade skipped you have no choice but to register them for the grade they are currently in, but for a child who is only math accelerated, while remaining with his age peers for other classes, the choice is yours. There are no advantages in registering them for higher levels, the test is not easy - very non standard questions, they have to use logic and combinatorics, not just simple arithmetic.
So Debbie, you can register your child for level 2, Dottie for level 5.
The test takes place in the evening, check out if there are locations near you, if no you can open your own site for example in a public library. I did just that two years ago and that is how we started.
Will be happy to answer more questions :-)
Ania