Which is hardly any time in the world of forums.
The way I did it was to download my firmware with Navifirm, and copy the folder containing the files to the location specified in the tutorial for "Easily Flash your 920....."
But I used NCS since the other easier tools didn't recognize my phone.
I don't see why it would download again if its already tehre, might have to make sure the folder containing he stuff is renamed a certain way to make sure its seen, but I don't know what to tell you personally other than to experiment since I'm not too experienced with it
But someone else probably will come along in a day or two. Patience grasshopper... its great in situations where you cant do much anyway.