Here is a handy script to create a csv file with file names and the date when files in a given folder were inserted:
<?php
 header("Pragma: public");
 header("Cache-Control: private");
 header("Content-Type: text/csv");
 header("Content-Disposition: attachment; filename=age-of-files.csv");
 $result = array();
 $handle = opendir(".");
 while ($datei = readdir($handle)) 
 {
 if (($datei != '.') && ($datei != '..')) 
 {
 $file = "./".$datei;
 if (!is_dir($file))
 $result[] = $file;
 }
 }
 closedir($handle);
 foreach($result as $r)
 if (file_exists($r))
 echo substr($r,2).",".date ("m/d/Y", filemtime($r))."\r\n";
?>