When I had a student that wanted to learn to build I used the 4*60 as the training tool and taught them to build while I was teaching them to fly with my trainer. When they were finished with the trainer after the solo the 4* was finished and they had there own plane. Only one was lost due to a crash but it was really the kids fault. He wouldn't keep the plane in front of him and when he was behind the pit area he was facing due east and got sun balled then lost the plane. I walked out three times and told him to keep the plane out in front of him but boys will be boys.
I had my nephew fly his trainer until the covering was falling off, from that he went right into a Kaos 60 without problems. Just build your plane and by the time it is finished you will be ready for it.