If you have children, you and your spouse most both file your personal tax returns in order to receive the full amount of the Canada Child Tax Benefit (CCTB). In order to ensure there is no delay in receiving your CCTB, you must file your return by the appropriate due date. Even if you are delayed and do not forward your tax returns until the end of the year, the government will still back-date any payments which were owed to you.
This is similar to many other government programs. If you are eligible for a GST refund, or the Guaranteed Income Supplement, your returns must be filed by April 30th in order to ensure your payment will not be delayed.
The payment you receive in July for these programs is based on your personal tax return from the previous year. In short, if the government owes you money, the sooner you get your tax return to their office, the sooner you will receive your funds.