Exit any of the 29 MTR stations on the map above between 7:15 and 8:15am on a weekday and passengers using an adult octopus card get a 25% discount on your journey. The important word to note EXIT, you can start your journey anywhere! The discount is also works with the connected journeys discount and lasts from 1 September 2014 to 29 May 2015.
Does this mean fares are going to rise soon?
Terms and conditions are here http://www.mtr.com.hk/archive/ch/pdf/early_bird_terms.pdf