Install the gyro and initialize it. Be sure that you have dual rates set up so that when you initialize it the servos are moving to the maximum position they will ever move while in flight. Check to make sure axis is responding properly ie if you roll plane left, the servos automatically deploy right aileron. You nose plane down and up elevator is given. You yaw left and right rudder is given.
Set the Cortex up on a 3 way switch such that you can switch between normal mode, hold mode, and OFF!
Fly the plane with gyro off and set all mixes. Then turn gyro on and fly.
If you decide to change mixes, turn gyro off to do so, then turn back on and fly.