You're all doing great
My wife started her turn today and seemed to follow the patter of my first day, first nap was just crying no sleep. Second nap slept almost straight away for 30mins, then woke and cried the remainder.
Here, I think you have already guessed, is where he tests out to see if things can be "normal" with Mummy or if she is also going to insist on the "new rules" of sleep. It can also be harder for some Mums if breast feeding has been used as a prop as baby knows Daddy can't offer the breast whilst Mummy can - I don't think you have this additional problem in your case but even so LO is testing the boundaries. Again she has done well to continue and to get through to nap 2 where there is improvement, helped along by LOs tiredness.
He’s never slept 6 hours i dont think, ever!
Wonderful!! So, the things I mentioned about the milk feeds, you do need to make sure enough is offered in the day in case he needs extra now he is going a longer stretch overnight. I think you know this already but I mention it as I know you will all be feeling tired from the last few days of disturbance (and the longer disturbance up to this point) and sometimes things slip our minds when tired.
Really, it was a great night to see a longer stretch of sleep even if he was still up for the day at 5.30am. The overall routine and WU time can be sorted out if it remains this early, we can help you shift it, perhaps better to wait another few days or so as his A times will be erratic just now through this sleep training period. It may be that he has a touch of OT prior to BT leading to an earlier wake up...or it could be that he is better rested having a more restorative night sleep (not spending so long eating) and so has finished sleeping which would need a later BT - we can probably work this out when things settle down a bit.
There is one thing you can try now with that 5.30 WU which is to go in at 4.30am and do a W2S (wake to sleep) here is some info if you are not familiar with it:
How do I address habitual wakings? (wake-to-sleep and other methods)Don't feel obliged to try this immediately, you might be enjoying that 5-6 hr sleep!! It is an option though, either now or later.
Is this improvement partly because he’s slowing learning to put himself to sleep or just because he’s so tired?
It's both really. The additional tiredness does help him to accept sleeping in his cot more readily and also to transition between sleep cycles rather than waking up, he will be tired. But also he is learning too, he knows that you are there, knows you comes when he needs you, so his confidence is building, this also helps him to be confident to transition sleep cycles without needing to fully wake and call out. He has less need to call out because he is learning every time he does you always respond - he needs you less (not more) as a result.
Keep going - you are all doing wonderfully
And it's only been a few days.