Sounds like what I went through
I got the fully favorable in Sept 07, and everything but the backpay went through within the first couple of months. But the SSDI backpay didnt arrive in the bank until June 08.
They were figuring everything is what they said, but I found that if you got anything from SSI or they are determining if you qualify for SSI it will delay the SSDI backpay.
I received a backpay for SSI, but didnt qualify to stay on SSI. When they finally got to the SSDI they deducted out what I got from SSI. This is what they say held things up. The SSI persons didnt release the case over to SSDI.
Finally I called my congressman, and within a month the SSDI was in the bank. Then I didnt get the letter from SSDI for 2 more months.
Sounds to me you are about to have a really good surprise in the bank