You may be unaware of your child’s instinctive readiness for making music but there are signs that should help you make that judgement. Here are specific suggestions that will aid you before starting private lessons:
Purchase a keyboard instrument (a portable digital keyboard may do the trick but plan to upgrade when lessons begin) and let your child explore sound before enrolling in lessons.
Once this exploration begins, notice how your potential musician experiments at the keys.
If the keyboard receives regular visitation, this is strong evidence that your child is ready to engage in lessons.