I had my daughter on Friday morning, checked out Sunday afternoon.  I think they took the picture on Saturday.  Tell the nurses you want to know when they'll be taking the picture so you can put him in the outfit you want ahead of time...one thought to share though.  I've seen these poor newborns all dolled up for nothing, in an outfit that's too big for them and they look miserable.  Choose something tiny (the ONE newborn outfit you keep) and make it something comfy.  I put my daughter in a tiny pink sleeper that snapped up the front, and she looked darling without being all fussy.  The nurses even brushed her hair!  I wouldn't trade that picture for the world!