I concur with Secret Agent on bleeding off speed in sharp turns with a delta wing planform. Also note that deltas are very responsive in roll but generally sluggish in pitch. On my A-4,a delta with a horizontal tail, I would let the model takeoff by itself without forcing a rotation. Also, I set a fair amount of positive angle-of attack to allow the model to takeoff without elevator input. The first turn after takeoff was always exciting especially on a hot humid day. Note that this A-4 was initially powered by a K&B 7.5 driving a Turbax I fan producing only about 6 lbs of thrust on a 9 lb airframe. Good luck on that maiden flight and let us know how if goes.
Regards,
Art ARRO