I did it soon after the quest was released. It does not seem to matter what storage container (dig spot?) you use in the place mentioned, but you may have to try it multiple times before it works. I can not remember if it tells you that it did not find the item, but if it does that means just to keep trying. If you don't want to wait for the dig spot to recycle into usefulness, there are at least 3 dig spots in every area mentioned.