Please help [been bugging me for ages!]

[N9ne]

PHP Code:

  $changeuser = '';
  if ($bbuserinfo['posts'] >= $postuserchange) {
    $oldnames = $DB_site->query_first("SELECT * FROM namelogs WHERE userid='$bbuserinfo[userid]' ORDER BY time DESC");
    $diff = time() - $oldnames['time'];
    $limit = (86400 * $dayuserchange);
    if ($diff > $limit or $bbuserinfo['usergroupid'] == 6) {
      eval("\$changeuser = \"".gettemplate("changeuser")."\";");
    } elseif ($diff < $limit or !$bbuserinfo['usergroupid'] == 6) {
      eval("\$changeuser = \"".gettemplate("nochangeuser")."\";");
    }
  } 


Ok there we have some code, heh. What I want to do, is have a variable which will say how long (in days) until the user can next change his username. I messed around with making new variables and such, but nothing is working for me! What variable do I need to set here so I can put it into the "nochangeuser" template, so it will display the number of days left until the user can change his/her username? Or is it more complicated?