Newborns are screened at birth. If your child missed that, the next practical windows are before pre-school (age 3–4) and before Grade 1.
Book sooner if there's delayed speech, frequent ear infections, or a family history of hearing loss — even a small hearing loss at a critical age can slow language development, and we want to catch it before it affects school readiness.
All children should be tested at least once before they go to Grade 1. It's quick, painless, and one of the best things you can do for a child about to start formal learning.