If he'll go down earlier for BT then I'd try that, thr is a chance he will wake the same time the next morning but having had a longer night sleep. Thing is, he could also do the same length night and wake earlier - it's a bit of a gamble. I'd try it for a couple of days though. It does sound like he needs more sleep.
The other thing you could go for - if he refuses an earlier BT - is to extend the second A time so that he sleeps longer for his CN, however this means later to bed for the night too as he will likely need a decent length A time before agreeing to BT yk?