you should be sponsored for a minimum of 1 year based on qatar labor law before you can transfer your sponsor to another company. But if youre company is willing to give you a go signal to find a new job and assured you an NOC..ask your sponsor to give you a six month No Objection Letter to be addressed to your new company. If your new company accept this, then there will be no problem. On December 2009, Only you can change your sponsorship. Goodluck.