If your child knows a lot of the material already, you might want to consider a grade skip for your child. If your child isn't technically old enough to start kindergarten, but knows much of the material already, you want want to consider starting him in kindergarten early. Although it may seem quite early to be thinking about this, it can take time to research what your school district's kindergarten goals are, what the policy is for grade skipping and early entry to kindergarten, and what you have to do to get your child a grade skip or early entry into kindergarten.
Once you find out all this information, you then have to work to get the task complete. Sometimes working with a school takes a long time. This is not something you want to wait till the last minute on.