Changing LCA Do i need Hard Copy of approved Petitions

Question

Hi Everyone,
         My H1B petition was approved on 14-Aug,2012 from Vermont center but I need to change LCA before going for stamping as i have changed project for different client.Still waiting for Hard Copy of Petitions.Do I need to wait for Hard copy for the approved  I129 PETITION to receive for filing New LCA for the  Client or My can Employer can file the New LCA for Chicago location without hard copy of approved petitions.Minimum time required for new LCA ? Please suggest. Thanks !!

Thanks
H1B Guy.