Google has not changed the Page Rank trend like after every three months in a year and change its
regulation often. Google updates websites Page Rank frequently in 3 months once. Previously updated on 3 rd May 2012 exactly in same day Google updates PR 2nd August 2012.
Google Page Rank (PR) Update in 2012:
1. Between 30 January, 2012 to 2 February, 2012 2-
2. Between 30 June, 2012 to 2 August, 2012
3. Between 30 September, 2012 to 2 October,
4. Between 31 December, 2012 to 3 January, 2013
Above referred Google Page Rank (PR) update dates are compulsory but, Google can also make little updates between those dates in 2012.