vvotan

Usually, the calendars are based on some physical processes, like Earth revolving around the sun. With the time spans around 10**24 years, the existing physics does not make much sense (since the lifetime of the universe squared, that is a lifetime of universe per every year of lifetime of the universe is still 6 orders of magnitude less than 10^24). In the current scientific world-view, in just around 10^14 years (one ten-billionth of your scale) there will be no stars left. So, unless you explain the physics of your universe, there is little we can do about inventing the calendar.