Well, it isn't our I-600 approval, but we did get form I-797C in the mail today. It is a Notice of Action and says "The above application has been received by our office and is in process." It then asks us to check the personal information included on the form, if all is correct (which it is), then we don't have to do anything!
I hope this is a good sign. It took a little over a month for us to get our Notice of Action with our I-600a! This time it was mailed on 10/15, received in Texas on 10/19, dated 10/21 and postmarked 10/22! To me that is quick!
So, our paper work should now be on its way to Newark, NJ. Hopefully we will get a speedy approval! And I also think that this Notice also means that all of our forms were completed correctly and we don't need to change anything or submit anything else. Fingers crossed!