I'm trying to remember what we did...I think I discounted any WU before 6am. So like you did, keep her in her room, lights out and then at 6 walk out then back in all 'morning!' Like.
Then I counted A from them with no nap before 8.30am. (So 2.5 hrs A min)
Day would then be like this
WU 6 (ignoring ew)
A 2.5
Nap 8.30-10/10.30 (I let sleep as long as he liked for both naps to 2 hrs) - encourage long naps or try to resettle.
A 2.5-2hrs45mins
Nap 1/1.25-3 ish (again up to 2 hrs)
Bt 6/6.15
I know it's a Long last A but it's inevitable really, and I think you can't push the first one much more at this age with the ew.
when you get a later WU you do have to push the a As though, so first one a little, then push the entire day out a little later IYKWIM. For us a few weeks of this and eventually the boys readjusted into a later WU and Bt and the CN was gone