Does Fate/Strange Fake take place in the same timeline as any of the Fate/Stay Night routes?
From the afterword of the first volume:


  I suspect many Fate fans are wondering, "This is set after the
  original Fate, but which route's future is it?" I hate to say this,
  but, "It's a fake, so it follows a mystery route." I'll leave the rest
  to your imaginations. In the extra chapter, the two "Observers" leaf
  through a lot of pages. You can assume that the "world's route"
  changes with each of those pages.


FSF is set in a parallel world, some years* after the Fifth Holy Grail War, as constant references are made to it: Shirou is obliquely mentionned as a creator of relics, Francesca Prelati took the mud of the corrupted Grail for her own purposes, etc.

*By my own estimation, maybe 2008. It was the year the April Fool's one-shot version of FSF came out in, but Flat Escardos's age is also an hint: in FSF and in El-Melloi Case Files, he is respectively 19 and 15, and El-Melloi Case Files take place during the year of the Fifth Holy Grail War, meaning 2004.