Let me preface by saying this is not a stupid "Can I kill their Emrakul/legend by putting in my Phyrexian Metamorph" question.

Upon resolving Show and Tell or Exhume I choose my Phyrexian Metamorph and my opponent chooses Elesh Norn, Grand Cenobite. At what point does the global +2/+2, -2/-2 buff happen? I know that off of a show and tell you can 'see' what the other player put in so you can name Griselbrand/Sneak Attack with a Phyrexian Revoker.

Basically I am wondering if I can choose to copy my Imperial Recruiter (or any other creature with ETB for others) with my Metamorph to get the trigger before both die, or whether Elesh Norn is already considered on the battlefield with it's global effect.