I would consider building a small living space in the gar and put that up first. Then you are on the property to keep an eye on things and can take your time. You won't need much room to get by for a while, and when the house is ready to move into, you can decide whether or not you want to keep the gar living quarters. Just a thought. My cousin went that way and it worked out well for them. When the house was done, they just knocked out the preframed walls of the living quarters in the garage, and hung garage doors.