I agree Monique - Blue Hour is so short that one has to be on site and set up well before that time. I generally try to combine my Golden Hour and Blue Hour shoots so that I get the best of both those lighting conditions, but things don't always work out that way.
I have had similar things happen to my shoot planning too. I had planned to shoot an architectural scene in a city that is 2 hours away and when I got there, there was a musical event going on that was supposed to finish well before sun down. My contact did not know about it otherwise I would have not bothered going down.
It finished right on time, but the large trucks that were there to pack everything up parked right in front of the building I was planning to shoot and golden hour and blue hour came and went without me getting a single shot.