My now 4yr old is in speech therapy. At the beginning of the year she started stuttering, we were given exercises with her but it got worse. We had to scale her everyday from 1 to 10. Each week we took this paper in with us. The CHN sees her for an hour a week. She has her ups and downs(mainly when tired) but is not as bad as it was in Jan 06. We were asked to make note of what we did each day too.
Maybe keeping a tally to see how he goes through the day and if it is day or night when he stutters.
Also as the CHN for any exercises or activities you can do with him.
I would give you mine but there is a 2yr gap and they would be at different learning levels. correct his sentences and ask him to think what he wants to say first. (It is hard for a 2 yr old though)