I was in London & Paris this past July 21-30. I had gone to 2 Hermes stores in London (no Kellys & only 1 Birkin Croc print) & all 3 stores in Paris. I went to 24 FSH twice on a Wed. 1st when they opened the 2nd around 2:30, I made it a point to look for the same SA who would tell me, "none available, but come back tomorrow around 3pm". I went there the next day around 2:30ish and it was like Christmas! Birkins & Kelly bags being shown. The SA who helped us the day before was busy so we asked another if there were any Birkins. Her response was, "No we don't have any in stock" didn't even bother to look in the computer or even pretend she was checking stock. We asked what all the other customers were looking at she said, "they are trying out the sizes". At that point we realized she didn't want to help us so we asked another SA. His response, "I will go to the back & check". He comes back saying as if it were top secret there was 1 birkin in stock which he could only show me in private. I truly lucked out cause it was the one I wanted.
You will find your bag at 24 FSH you just have to be there around the time of delivery, be persistent and make sure you find a helpful SA.
Good luck =)