You should apply for the Canada child benefit (CCB) as soon as any of the following situations happen:
your child is born
a child starts to live with you, or returns to live with you after a temporary period with someone else
you begin, end, or change a shared custody arrangement
you get custody of a child
you, or your spouse or common-law partner, start to meet the eligibility conditions under Who can apply
If the child started living with you more than 11 months ago, you will need to provide additional documents.
You don't need to apply separately for related provincial and territorial programs. The CRA will determine your eligibility when you apply for the CCB.