Bruch Violin Concerto Continued

My son's been working on the 1st movement of Bruch Concerto for a couple of months now. It is progressing slowly but surely. The last lesson was spend on the first note for about good thirty minutes. It is forte, but still needs to be clean and has to have a room for building up the dynamics. It is advised that smaller notes (8th and 16th notes) need smaller bow and use of the wrist for smoother sound. Oh, so many things to pay attention to!!! My son tends to have dynamics up and down like a roller coaster, but this has to be one big crescendo.
Also, his weakness is his bow hand. He lifts his pinkie off the bow and that makes his sound weak. His assignment for this month is to keep his pinkie on the bow at all time. It took good two weeks for him to fix this problem. I had to tell him every time his pinkie was off. I know he is so tired of me butting in, but now I don't have to remind him that often any more:) It makes a big difference in sound especially with his small hand, he needs all the weight he can get from his fingers and elbow. He was busted at his last lesson that he was not using the metronome during his practice. I guess it was very obvious to his teacher since his rhythm was all over the place. Now he is using it all the time. Hopefully it will show at his next lesson.