Your ds sounds a bit like my ds10, but mine was born with special needs and delays so he was lacking with his gross/fine motor skills, etc. I had my ds tested at 5.5 and then at 6.5 yrs old, but he did not fully cooperate with either test so I did not get accurate scores.
One of the dilemmas with testing a child at age 5-7 years old is that they can be unpredictable. I know that may sound dumb, but in terms of possibly spending money (potentially lots) and a number of headaches to boot - the unpredictability is something to bear in mind. Kids can be sick, tired, going through a growth spurt, dislike the tester, or just going through a bad day - any of which could negatively affect test scores.
If you have a very bright kid, they can be determined to hide their gifts, fail to see the benefits of the test in the first place, and deliberately self-sabotage (ie. counting on their fingers like my son did) simply because they don't want to be tested! It can be infuriating to say the least.
So my advice would be to see if your local public school will administer the Woodcock Johnson for you for free. Mine did - even though my son was in private school and then homeschooling when he was tested. You could request testing be done. Sometimes, the request has to be done through the special needs department or you may have to conveniently suspect special needs to make such a request. Regardless, this may be an option and may still be helpful to you. It may still give you some details and information about your ds. Also, you could always combine what happens with the testing at a public school system to any testing done privately. That can really help as well.
Privately, you could find someone who will administer the WISC. However, I'd try to find someone who has experience with testing a possibly pg kid and is able to get reliable scores from your ds. Many testers don't have experience with this population and see you simply as a 'tiger' parent and/or know how to deal with your ds. Be prepared that you may have to shell out big bucks for private testing.
I had ds10 tested because 1) he accelerated quickly through a private school's pre-k to 2nd grade curriculum, 2) knew he was possibly pg then BUT had special needs as well, 3) needed an explanation for some of his behavior, 4) what to do with this martian in terms of any schooling, and 5) access to programs.
Good luck!!!
