Krisflyer Gold status with 4 flights in conjunction with Amex Platinum and Shangri-la, how does it work?

[Berational]

Hi everyone, I am a newbie to this forum and I would like to get some advice on how to plan my trip in order to make the most of the promotion offered by Amex Aus. Since I have an Amex Platinum card and I have been a member of Krisflyer members since Apr 2008 but my current silver status is valid till Sep 2019. I am thinking of taking a return trip to Japan in Oct this year and stop over in SG for a couple of days on my return leg to Sydney. My question is once I completed this four sector trip, would I be eligible to be upgraded to Krisflyer Gold for one year, and how long will I be able to keep the Gold status, does the one year period starts from the date I get upgraded OR it actually starts from my membership starting month which is Apr every year? In that case, I would be only on Gold for 7 months, not very attractive!Much appreciated for your advice in advance! Cheers~~~