I still have not received an email from USCIS acknowledging receipt of my I600. I have been obsessively checking my email - even more than usual. I finally emailed my agency today and learned that my I600 wasn't sent until this past Monday, 1/21. Argh. This means it could be two more weeks before I even receive my acknowledgement.
I just have to make it through this last waiting period and then I am on my way to my baby girl. I can do it! I think I can, I think I can. : )