Hey, sorry, just been away. Hmm so if I'm understanding correctly, on days where there are after school activities, he has to be awake between 3 and 5:15, right? Looking at your last working routine, I wonder if you could shift your day a little, to something like:
7am Up
11-1 Nap
5:15-? Shorter nap/CN (earlier on days when you can, or perhaps he might fall asleep on your way home from after school activities?
7:30/8pm BT depending on that pm nap?
I realise that's only an ideal and relies on you both being able to shift the day (over a weekend, perhaps?) and on him napping well at nursery - but then it looks like he's starting to manage longer naps there, a good sign