I received the letter in the mail today from the USCIS saying that they have received my I-600A application. I mailed it over a month ago, so it's nice that they finally acknowledged receiving it. It's not a big step, but it's something. At least now I have an official referral number for my application. We're still waiting for our fingerprinting appt. letter, but from what I have heard that usually follows the receipt letter within a few days. The appt. will probably be about 2 weeks after I receive that letter.
So, here's hoping that we get our fingerprinting appt. letter by the end of the week.