Here I am, after one week.
The plan was 1:00-5:30 and ~16:30-18:00.
I've made a little bit of progress, but I'm still struggling very hard to get a solid 1.5 hour of sleep in the afternoon. In the afternoon I'd usually fall asleep for 5 minutes (get a quick dream) and then it would be hard to fall asleep again. I don't think I've ever managed an uninterrupted 1.5 hour in the afternoon.
Then if I do happen to sleep in the afternoon it's a challenge to fall asleep at night before 2:00 or so, which in turn makes me very sleepy at 5:30.