afewquestions

Am I correct that you have been following your case online?
If there is an interview date set your online status will state the date and that they have sent a letter. Have you got the set date for the interview? The letter says the date too but you would already know that from checking online. The letter tells you the location, time and what to bring.
If you haven't received notice that your appointment has been scheduled they won't have sent you anything new...
If not keep waiting, the scheduling all depends on the local field office and how backed up they are, there is nothing to say they should send you an interview date by a certain date/time... Some people get scheduled quickly and others (like me) sat in the waiting for an interview to be scheduled for roughly 110 days...

If you don't have an interview date set, that "if you don't receive a notice by" part of your status is an inaccurate fluke that came with the new system update. Mine says I was meant to have a letter by November 5th, but in all reality I know that my interview will probably not be scheduled until late December, with an interview date sometime in January or early Feb.
You won't miss the interview. When you actually get scheduled, your status will update again with the actual interview date.

Wow we are almost on the same timeline, even the engagement! Should be interesting to see how quick we get NOA2.

Her offering the information that you will be filing for a K-1 visa will show that she has immigrant intent to CBP. It may or may not affect the length of stay she is given, that will be up to the officer. If she is not asked about it, she doesn't have to offer the information, but if she is, she should answer truthfully. She just needs to show proof of ties to her home country and her travel intinerary if asked.

Hi!
I didn't stay for the 6 months that I was given. I just stayed for 20 days since at the time I was still working in Argentina, so your girlfriend's case seems to be different (I still had strong ties to my country) Why they gave me six months? I have no idea. I guess it had something to do with the fact that I had been in and out of the country on that B1/B2 several times and I had never over stayed, I guess... they just stamped it for 6 months. I think the best thing you can do is just be honest at the POE, tell them that you are here waiting for the NOA2 but that you are totally aware that you have to go back for the interview and that you don't want to overstay your b2.
Good luck!