I have the same problem but the users were created with API, I do not know if there is a better way to solve this problem. I add on bottom a jquery trigger to do the redirect (moodle 2.8).
_____
$lastName="Usuario VM";
if($lastName==$USER->lastname){
"<script src='https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js'></script><script>$(function(){ $('#id_submitbutton').trigger('click'); });</script>";
}
____