Compensation under this Division is not to be enforced before the expiration of one month from the date of the determination under section 66 or, if a notice has been given by the planning authority under section 67 (1) , until after the expiration of 3 months from the date of the notice or, if within that period a variation of the scheme is submitted to the Commission, until that variation has either come into operation or been disapproved by the Commission.