It's a good idea to test your child, if you can afford it easily. It is best to test early. Children who are tested early are generally more successful than children who are tested later.
The best is to use a psychologist who is certified to test young children.
Ours came to our house, since my son was only 4 or 5 at the time. She was especially sensitive to how the child feels. Her goal was for him to feel comfortable so that he can perform at his best, without any anxiety.
The reason I think it is a good idea to test is that there are a lot of wonderful programs that are specifically open to gifted children. These can be private or public programs, and most of them will accept the results of a private test performed by a certified psychologist.
For example, there is a great online program from Stanford University called EPGY. It is open only to kids who test above a certain percentile.
In Califronia in the Bay Area there is a program called "Liceum". It is a wonderful program, open only to gifted children. It offers great seminars to small groups of children. There are also public programs in different school districts all across the US. Each district has different programs. They are enriching and interesting, and not necessarily part of the school program. Going to these activities enriches children's lives.
If you have your child tested now, you can use the results of the test indefinitely, and you don't even know about programs that will take place in the future, where you will want your child to participate.
There is no risk, if you choose a good psychologist, the experience should not be detrimental to your child's wellbeing
.http://www.all-gifted-children.com