The government will go back up to 10 years for CCB. If you qualify it is possible that they send you the complete amount in one lump sum. You can contact CRA directly and what we recommend is create a CRA "My Account" and when you go into your "My Account" all your updates will be there for you. How much you'll be receiving and when.
https://turbotax.community.intuit.ca/replies/2647704