What is the definition of effective notice in the context of retroactive child support?

With respect, this constitutes an error of law because it fails to appreciate the meaning of effective notice as set down by Bastarache J. in D.B.S. where he held that effective notice is "… any indication by the recipient parent that child support should be paid, or if it already is, that the current amount of child support needs to be re‑negotiated." As I pointed out above this definition of “effective notice” was adopted by Cromwell J. in Kerr v. Baranow. Cromwell J. made this definition subject to the qualification that it applies as the default commencement date for the payment of retroactive spousal support unless there are circumstances where a judge might otherwise exercise his or her discretion and select another commencement date, such as the date upon which there was in fact a material change in circumstances.