Couple of years back I was watching bike racing on TV, and Magnus "Big Maggy" Bäckstedt was sharing commentary, and they were talking about TT bikes and the different position.
Maggy said that when ever he knew he had an important TT coming up, he used to set the TT bike up and leave it ready in his garage, go out and do his planned training session on the road bike, and when he got home jump straight on the TT bike and blast an "out and back" for an hour just to keep the feel of being areo.
It's something I have tried to do since I bought a TT bike, and after a winter of road bike, and MTB, boy does the TT feel strange ! But I can get back into being aero after a couple of rides...
Sadly the only comparison between Big Maggy and me is the big part !!!