ArtMetal

I just bought a piece of 14kt white gold strip that is 6mm wide and 2mm thick. I want to create a men's ring with a hammered finish. My question is, do I form and solder the ring first and then hammer it or hammer the finish and then form the ring? I'm concerned about the metal stretching when I hammer the finish. Can someone please tell me the proper procedure for arriving at the correct size (12.5)? Thank you.