During my college days the professor would take roll call for attendance and I would sometimes not be able to say “present” in time and would be marked absent. So I can relate to these type of situations. Over time I’ve come to realize the only thing in my control is the way I experience my stutter. This includes the anticipation, the actual physical act of stuttering as well as the feelings and emotions after the act. A small step I recommend that could help is letting your professor know of your predicament. Though I understand this may not be the advice you were looking for, I truly believe it can help reduce the negative emotions around the stuttering experience.