I would highly recommend buying or borrowing a balance buddy from a friend. It completely saved my back and made my DS 100% confident that he was not going to die riding his bike. We took him to a large parking lot at the high school where there weren't any obstacles to hit or cars to worry about first. It was really difficult for him to trust that he wouldn't get hurt because he had taken a bad fall the first time at a friend's house.
Riding a scooter seemed to mess up his bike balance- I don't know why but to him they require very different balance. Swimming made his bike balancing far better! He was riding confidently at 7, about two to three years later than most of his friends. It took several months of practicing before he was very confident.
