What A time did you have after the 40 min nap, can you remember?
Honestly I do not remember exactly our different routines at different ages.
I do remember my DS always had a very short last A time. Whilst i can't remember his times something like a 2hr last A time sounds like that's what he might have done (long first A, long nap, then either 2 40 min or 1 40 min nap, I think at 7 months it was likely two and then in another couple of month maybe 1 CN, short last A to BT and quite a short night). I'm trying to remember what time he ate after his CN, I think he woke something like 4ish and dinner about 4.15/30 and I think BT was 7 with WU about 5/5.30am.
We did not have a perfect routine btw
Another thought, if we manage to get back on track to where we were, won't we just end up in the same position again?
Let's see where he is up to in a couple of days, let him have a chance to catch up if he is OT and see if any of this is permanent or was a one off. If he wants to nap earlier, say 9am, every day and sleep for 2hr it isn't really a problem other than it encourages him to keep waking very early which I'm sure you don't want.
When he wakes early would you try a feed and back down? I've no idea if he would go back down.
Just thinking it could kick start an improved routine so really it's just one day it needs to happen so that he can have a sleep then wake (you cap if needed) a decent A, nap at a reasonable time...so that the whole day can move on and by Monday he is waking a bit later and not nodding off on the school run.
it's a bit of a long shot but it could work.