Mr&Mrs G.

I'm happy to put the spreadsheet together. I spend more time than I'd like to recall working in Google Docs and obsessively crunching numbers gives me the illusion I have some sort of control over this terrible process 
 
I plan to include: Priority Date, NOA1 (defined as date they assigned your case), Service Center, and Country for now. And then we can start adding RFE (knock wood there are none in this group!), NOA2, etc. as things finally start moving!

As I understand it noa2 means your I-130 has been adjudicated and sent to the NVC for processing. Then the petitioner receives a welcome pack from NVC with the I-864 included. 
 
To me it seems to be the most difficult for those of us who live abroad with our American wife or husband. Best to try be ahead of the process because some of the questions are just a little tricky and can be misunderstood especially if you are using a joint sponsor.

It means they accepted your application for processing, if all the info on NOA1 letter is correct it's basically a waiting game for USCIS approval, or you can start gathering all NVC documents after approval (Nebraska is currently taking 6 months for approval).