Ive searched other feeds in relation to interviews. They would usually request it before your pre-arrival
Many users have been reporting that the Manila VO always sends the pre-arrival invitation first before DM or PPR. I guess this is how Manila does theirs while other visa offices do it at a different stage. I was also reviewing the consolidated spreadsheet as well doing a temporary filtering of the excel document specific to Manila from each of the months prior to August 2017 and from what I can tell those who have reported their BG, DM, and PPR, these all occurred all on the same date, a couple of them the BG, DM, and PPR all occurred at the same time. There were a couple where BG and DM are a few days apart or perhaps didn't report their timeline. Based on my review of the trends, it appears once you get a DM status, your PPR is also issued too.
If you hear anything new with your application as well or any updates, please feel free to tag me and let me know. I shall do the same. Gods timing for both of us will be here soon and we will be reunited with our loved one(s)