Many parents realize early on that their child is unusually bright. The child may be extremely verbal, adept at putting together jigsaw puzzles rated for older children, or a self-taught reader before reaching school age. The type of questions the child asks may show particular insight and depth. Some gifted kids have early motor development as well, and literally keep their parents running in those first years! There are myriad ways that a young child will show his intelligence, and parents often recognize brilliance before the child reaches kindergarten age.
It may be tempting to get the child recognized as gifted as soon as possible. Parents want proper placement in school for their gifted kids, and they want to ensure that their precocious child is given appropriate challenge. There are selective schools that require IQ tests for admittance. Therefore, it is not uncommon for a private test administrator to be engaged when the child is three or four years old. It can cost hundreds to thousands of dollars for a full assessment. Unfortunately, testing for preschool age children is a gamble. Even the most intelligent child may be uncooperative, have trouble following what may seem to be ridiculous demands, or they may simply find the whole process to be too much. An introverted child may be unable to open up and express herself in front of a stranger. My own child, at age four and a half, shut down after completing just two subtests on the WPPSI, and refused to speak. In hindsight, I should have known that she wasn't ready for the experience.
So just when should you have your child tested? Unless there is a pressing need, such as for entry into a special program, I'd recommend waiting until school age. Most experts agree that the best age for accurate results in intelligence testing is from around six to ten years old. Most kids at six are able to sit still and do their best. After age ten, there is a greater chance of hitting the higher limits or “ceiling” of the test, resulting in a depressed score. Some extremely gifted kids may hit these ceilings even earlier. Older children may do better to take an out of level test such as the SAT or ACT. These are not IQ tests, but they do give a very good idea of a child's academic abilities.