Of course, this is all give-or-take when it comes to exact timing. The world as a whole doesn't have a universal calander, with each nation leasuing time differently. An elf may never notice twenty years passing by while a human would just be beginning to live on their own. Combined with different cultures and idealology, getting an accurate measure of the before time is an exercise in fruition. But youre free to do the math as it pleases you.