I make a particular point of not discussing the AI untill all the presolo exercises are mastered. Students should learn to recognize the bank angle and the aircraft attitude by what they see looking out the windshield. I have found too many students from other instructors were going head down at the same time they were rolling into the turn. This is particularly bad with ab initio students who have been polluted by MS Flight Simulator. I always cover the AI if I find the student flying the instruments instead of the horizon.