You're welcome. I don't know exactly how long DOS grants the recommendation after they receive the letter from the state. In my case, my employer applied for my waiver through Conrad 30 on the first week of October and the next notice I got dated Nov. 3rd was from the DOS saying "the Department has reviewed the request and finds it in the Public interest and recommend to the USCIS that the waiver be granted to the exchange visitor..." You see, I did not know when the state of California sent my recommendation to the DOS.
By the way, why is it that you don't seem to be sure which state the letter came from? It should be where you will be working. So are you going to work in New Mexico?
I-797 is the form (notice of action) which the USCIS sends to inform applicants that their waiver request has been received and then later that the waiver has been approved.