You can apply for the CLB as soon as your child is born or at any time until they are 21 years old – if they were born after January 1, 2004.
If you forgot to apply or just didn’t know about the Canada Learning Bond, please apply as soon as you become aware of it so that your child benefits from the grant.
Of course, its better if you apply right away so the funds can start to earn interest which will result in more money for your child’s post secondary education.