Should my child learn an instrument?

When's the best time to introduce an instrument like keyboards or a guitar?

These instruments can actually be introduced almost anytime. It might just depend on how it is introduced and what we expect them to be able to do with the instruments given their ages. 

There more important question might be, why do I want them to learn an instrument, what can they feasibly learn given their current age and is my goal realistic? 

Early years - informal use of instruments (whether real or toys) that promote an appreciation for them. Keep in mind that children will be banging, shaking and making things up, and it's a fun meaningful experience that you can have together. 

Toddlers and preschoolers can get more structured instructions, but hopefully this can still be fun and play-based learning for instruments so they can identify beats and melodies. 

The capacity to hold longer attention and understand more complex instructions from a teacher might not start until they are about 6 years old. 

*Note: Each individual child is different. Their readiness might present earlier or later. If you join music programs or look for teachers, look for the rightness of fit with the teacher, your child and your goals. 

Happy playing!!!