I am currently holding a TN which will expire on April,2009(I extended it by mail on March,2008). In the meantime I got another better job(appointment letter) and being the joining date July 1st,2008, I can only go to border and get TN transfered. My question is now, what will happen to my current TN if the new TN is denied. Can I continue to work with my current TN? Is sending by mail has lower risk? How many days it take for the premium service?