"Subscriber Certificates issued after 1 July 2016 ... MUST have a Validity Period no greater than 39 months", which means that the effective date is 2nd July 2016. But previously, BR v1.4.3 section 6.3.2 said "Except as provided for below, Subscriber Certificates issued after 1 April 2015 MUST have a Validity Period no greater than 39 months", which means that the effective date was 2nd April 2015.
"Subscriber Certificates issued after 1 March 2018 MUST have a Validity Period no greater than 825 days", which means that the effective date is 2nd March 2018.
BR v1.5.6 section 6.3.2 says...