If you did a slightly earlier BT Laura (say 6/6.15pm), would he wake up even earlier?
As he had a day of it y'day at the hospital, then if I were you I'd probably consider a nap today, just to get him back on track a bit & keep OT at bay. Also he went to sleep later & (worse case scenario has been awake since 4.30/5am).
I guess you haven't ruled out the possibility of his leg/hip bothering him & causing him to wake?