Start in doorway from seated position. Toss the bike in a huge gear. No killer headwind. Ride from the tops. If you need drop a shoulder or an elbow into the doorway once you are going. Also, as you start to get a bit more comfortable, move to the hoods, the drops or even stand. Then start climbing down gears and/or up in cadence. Lower wheel speed means more difficult staying upright. Once you can do that with no incedents, you might consider in the middle of the room far from hard sharp objects and use a chair to start out. Eventually you will be able to sprint lightly, ride with no hands, look over both shoulders and use your TT bike. Eventually.