I second the PPs who've suggested making a list of why you want to have your child tested, and what kinds of benefit you see from the testing.
My daughter was tested once, when she was 4 years and 2 months. (I just pulled out the paperwork.) My son was tested twice - once at 4 years 10 months and again at 8 years and 11 months.
My daughter's testing (a full battery of tests including the WISC-R) got her access to our school district's Gifted program. My son's first round of testing was inconclusive, although it did give us some early warning that we might be looking at a learning disability. My son's second round of testing got him access to the school district's Gifted program, starting in Grade 5, but also confirmed a fairly severe learning disability.
So, basically, we tested two four year olds, and only one test actually told us anything useful. The other one had to be redone when the child was 8.
Testing is expensive! We were lucky in that my husband's insurance covered most of it, but we were still 300 dollars out of pocket for each round of testing.
We did not get an IQ score for our children's test - we got percentiles and grade levels. I have never shown my children their tests, and never will. They once asked me what their IQs were and I told them they're both smart enough and beyond that it just doesn't matter.
And btw, gifted teenagers are just that - teenagers. Most of the time, unless they're doing something like winning a math competition, you can't tell them apart from any other teenager. A four year old dragging a hard cover volume of Harry Potter around is immediately noticeable and causes comment. A 14 year old with a copy of *any* book - not such a big deal.
I don't think learning is a race, any more than growing up should be a race. Take your time, make friends, wander off on side trips, admire the view, and be thankful that you can pull your child out of school for trips to Disney without adversely affecting their education.
Have fun with your bright little boy!