I waited about 2 months for my letter, then another year or so for the hearing date. I know it cost more, but be sure to send all mail using a return reciept from usps.
True its best to double check everything.
I been going through this stuff now since 2002, finally had my hearing last Dec ( Fully Favorable), and should recieve my first check next week. Having several surgeries since 2000 thru 2007 made it tough for me to follow up, and believe me I felt taken advantage of.........If your able, follow up, and make copies.