Stephen Hawking writes about the beginning of time, but few other people do. People who write “from the beginning of time” or “since time began” are usually being lazy. Their grasp of history is vague, so they resort to these broad, sweeping phrases. Almost never is this usage literally accurate: people have not fallen in love since time began, for instance, because people arrived relatively late on the scene in the cosmic scheme of things. . . . If you really don’t know the appropriate period from which your subject dates, you could substitute a less silly but still vague phrase such as “for many years,” or “for centuries”; but it’s better simply to avoid historical statements if you don’t know your history.
Thank you, Paul Brians, of "Common Errors in English." :-)