That worked for me in my recent course. I photoread the material as soon as it was handed to me. So activation followed on almost immediately. Since I couldn't hear the instructor very well I was relieved to find that I had enough cues and was activating it during the class anyway.
If your instructor were to say to have read a certain part of the book before the class I would be inclined to do some activation of those sections. It makes it easier that's all. When advised to read certain sections I did my superread and dip in the 10 minutes before I left the class rooms at the end of the day. This was just to see what areas I felt I needed to go into with greater detail. I wound up not opening the text anymore at home (I guess I'm like any student when it comes to doing my homework faithfully 
)
It's sure worth trying to see what results you personally get.
Alex
Alex
