Make a mark on the string to represent your own life, one millimetre for every decade.
If you're very lucky, your life will be one centimetre worth of string. The previous section was designed, not to give you a sense of your own insignificance, but to show how immense geological time is.
Not only is there lots of it, but it is also on a totally different scale.
You've reached the beginning of the universe, 15 billion years ago.
Look back along the string, and think of the first mark you made, representing your life.
This order can be worked out independently for several different places.