What time period is required for children to get the citizenship?
They have to be PR but no certain time limit, it is the parent who has to qualify. This is from the CIC website:
To apply for citizenship for a child under 18, make sure the following conditions are met:
* the person applying is the child's parent, adoptive parent or legal guardian
* the child is a permanent resident, but does not need to have lived in Canada for three years and
* one parent is already a Canadian citizen or is applying to become a citizen at the same time. This also applies to adoptive parents.The best example would be if a PR has a baby outside Canada and sponsors the baby for PR. The parent can apply for citizenship after living in Canada as a PR for 3 out of the last 4 years. The baby may only be a few months old at the time but still goes on the parents application. Same if a PR had not sponsored a child on the initial application but does it later. The child may just have gotten their PR but if the parent qualifies to apply for citizenship, the child goes in on the same application.