You may sign the log at any time you wish however to log a find and earn a smiley for this cache you must prove that you have moved a Trackable such as a Travel bug at least 150 miles (241 Km) from the cache you found it in! It might take some work to remember what trackable in your past you have moved a great distance, so this could prove a little challenging especially to newer cachers! NOTE: DROPPED TBs only count in PUBLISHED caches - inventory unpublished drops will NOT be counted.
Here's an Example of you to prove your challenge completion in the log.
Please list only the REFERENCE CODE that opens the Trackable Page on Geocaching.com (the one that starts with "TB") and NOT the secret code you use to log the TB normally.
Example:
TRACKABLE NAME: Donkey TB (Ref No TB345HR)
CACHE RETRIEVED FROM: GC33PV7 on 11/23/2012
CACHE DROPPED OFF IN: GCWGVT on 12/12/2012
TOTAL MILES I MOVED IT: 200.6 mi