kirri

Yes, I contacted the embassy when my status changed to "Ready". But it was in February when the embassy wasn't issuing any K1 visa, so I had to wait. I contacted them again when the situation changed (based on Update to National Interest Exceptions).  I had my DS160 done before that. Then it took them few days to get back to me and I was finally able to schedule my interview online and you can see the list of documents you need to bring to the interview on the confirmation page I think. But it has been the same for some time.
 

I believe that K1 visa application is enough to prove your relationship. Fingers crossed.