These dominoes all fall in the same order - to the point where I'm going to start timing them to see if there's consistency. Start game, use controller to get where you want, plug G923 in, there's zero FFB, start your running, I'd say 6-8 minutes later the FFB suddenly kicks in, you race for a while, 15 or so minutes later the game can no longer connect to the servers, all progress is lost. Wash, rinse, repeat. I've lost several Time Trial personal bests already because as I cross the S/F line it immediately tells me it can't connect to the servers to register the lap time.
EDIT: I've timed a few instances of loading the game up and going straight to Time Trial. After plugging my wheel in, it's approx. 6:15 before the FFB kicks in. My server connection was lost approx. 4:10 later. All times I did this were within a few seconds of each other, so it's very consistent. Hope that helps in some way.