I actually found a cache before it was placed. It had been published, but the cache owner didn't have it placed yet.
My log for this one:
FTF!!!! I saw this one this morning and decided to leave for work a little early to grab it. I almost got there a little too early!!! I found the obvious spot, but no cache, just a box of crayons. I looked around a bit more, but was convinced that I had the right spot, so I went back to the car to get a piece of paper to sign and log my find. As I got back to the road, a car pulled in behind me...the cache owner with cache in hand!!! Turns out that the cache wasn't quite ready to go when published, and he was just ready to place it then. After verifying that I had indeed found the right spot, he allowed me to sign the logbook. First time I ever got to find a cache before it was even placed!!! TFTC and look forward to more in the future!!!