get insert id - SOLVED - this->db->insert_id()

[eluser]Colin Williams[/eluser]

Note: Because mysql_insert_id() acts on the last performed query, be sure to call mysql_insert_id() immediately after the query that generates the value.

http://php.net/manual/en/function.mysql-insert-id.php

If you do it on, say, the next immediate line, it's going to be accurate to the millisecond (thereabouts). I personally have never had anything funky go on.