i bought a property in year 2010, signed the S&P in October 2010, VP by early January 2011

is the following calculation correct?

First year - 30% - Oct 2010 to Sep 2011
Second year - 30% - Oct 2011 to Sep 2012
Third year - 30% - Oct 2012 to Sep 2013
Forth year - 20% - Oct 2013 to Sep 2014
Fifth year - 15% - Oct 2014 to Sep 2015

which means if I sell my house by October 2015 onwards I don't have to pay any RPGT?

any sifu please advise... thanks! 

There is a grey area, whether it is based on SPA signing date or stamping date.