As soon as we finally know we are about to pick up the visa. I bought her a plane ticket.
I gave her a two week lee way. She then just went to CFO. Same day she got her CFO Sticker.
One thing I would highly highly suggest is to bring ALL K1 paperwork so it saves you some time.
Depending on the counselor she was assigned to - some are easy to deal with and some will give you even some oddball requests.
They want some proof of pictures? no problem - her folder has pictures
They want to see to see the Affidavit of Support ? no problem, we have it.
Just be ready. Every questions the counselor had - she just answered truthfully.