Hiya, I was also diagnosed at the age of 21 (back in June) so I definitely relate to this situation.
11.3 is pretty normal just after diagnosis, my bedtime readings were constantly above 14 and as high as 19, but they do settle down eventually. A friend of mine who was diagnosed in February reassured me that you have to be extremely off the ball to return to DKA levels.
Starting carb counting already is very good, as long as it’s just counting. As stated previously, it’s best to eat normally so that you can see how much insulin you will need. At this early stage, corrections may muddle things (unless told by a DSN) but I could be wrong on that and someone will hopefully correct me if that’s the case.
Wishing him well as he starts this steep learning curve 🙂