All Canada pension plan benefits are associated with a retroactive period of 12 months, and that applies to everyone.
Even if a person applies for a pension at the age of 67 and would like the pension to be retroactive to the age of 65, the limit of the retroactive period is nevertheless set at 12 months. In future, if people are automatically enrolled at 70, the 12 months will amply cover their needs. They will incur no loss. This will be very positive for the future.