Even with a timer, if you are not in the map AND in the specific area, chances are high you will either miss it completely or not get a Gold reward. Some of these FATES only have 2-3 waves of trash mobs. These FATES will be zerged down in a minute if a few good geared people are around. I am done with my weapon and will never do it again but I still hope they announce to change the spawn times for all FATES needed for the books.