AIP GEN 3.1, para 4:
Documents and charts issued in accordance with the AIRAC cycle
become effective at 1600 hours UTC on the day prior to the
nominated date unless otherwise notified; eg, a document with an
AIRAC date 26 Jun becomes effective 06251600UTC (ie, during
Australian Eastern Standard Time, becomes effective at 0200
hours local on 26 Jun).
EDIT: Beaten!