I let him to do the self study, and occasionally he needs a little bit help from me. He seems to have very good math instincts, and sometimes he finds more elegant way to solve problems than me.
Thanks a lot for reminding me not being too pushy. I will be very watchful and let him to take the lead. So far he seems to enjoy it a lot, but if he gets tired of it, I will call it a stop. I do not want to burn him out. However he seems to like it so I will just let him drive.