As far as I know you can't find this as a list on project-gc, but the "Map Hidden month" function, combined with "From / to hidden date" (e.g. May to July 2000) and no selected area will give you a list of the very old caches worldwide. Not in order of the oldest, since GC-numbers does not always correspond with the actual order they were hidden, but it will be a limited number to search through.
If you have found the old months, use a profile name of someone who hasn't.