We have an upcoming K-1 interview in Peru and still are waiting for co-sponsor documents which
probably won't make it in time.

I called the consulate in Peru and they said we could re-schedule, and that it would take
about a week to get a new appointment date, and the new appointment would be approximately
a month after that. For us, even if it was delayed three months it would be fine.

However, can they be trusted at their word?

Has anyone successfully re-scheduled an interview in Peru?

I have not come accross anyone on here that has re-scheduled their interview. But, from what I see the Embassy has improved quite a bit and there should not be any problems.

We still havent received anything by mail, but we just called the embassy
and they say that our interview has been re-scheduled for approximately
3 weeks after its original date.

We rescheduled our Peru embassy interview back in March. We had a lot of problems in that we were told one date, and the system later had another date. No idea what happened. I was shocked when I called a week later and was told of another date. I had already bought my plane ticket but decided not to risk changing the date again and just accepted the system date. Morale of the story is call often to to confirm the date.

Also, the new packet won't go out until exactly a month before your interview date. Best for you to call and request that a copy be left at the Embassy for your fiancee to pick up. You'll likely be in Lima anyway doing all the police and check-ups. All you really need from the new packet is the new invitation letter. You can use the rest of the original packet 3 while you're waiting.

The packet with the updated interview date came in the mail.