Zeitgeist starts logging from the time its installed. It can not dig into the past.
However we have a workaround to retrieve the history out of a folder and inform Zeitgeist about it. Simply download the following script
then use it like this:
python history.py /path/to/folder
/path/to/folder being the folder you want to pull history out of example: /home/seif/Documents
also for those devs who love emacs or vim