First .. there's no need to calibrate the compass before you fly.
And it doesn't matter where you fly.
If the map isn't showing, you can confirm that the home point has been set by checking the green GPS - Ready to Fly banner on top of the screen.
Also the distance showing at the bottom of the screen.
Before the home point is recorded, it shows N/A.
When the homepoint is recorded, the distance shows.
That's the distance from home so it should be a very small number.