only 7 episodes left to introduce audrey and big ed...

It's going to have to be a busy seven episodes to properly wrap everything up. Given that part of the rationale for having this new season was because so many loyal fans were unsatisfied with the unresolved plots at the end of season 2 a quarter of a century ago, and with evil apparently winning, hopefully they pull it off and give fans a more rewarding conclusion.

Hmm. It seems to be wrapping up to me.

Coop escaped the Black Lodge (or mostly escaped).
We have an update on nearly all the characters from the past.
We know how the evil of BOB started.
The FBI has gotten really close to the evil. They located Major Briggs and murdered Ms. Whatshername.
Coop ate cherry pie and seems on the verge of escaping the Dougie purgatory.

I don't suspect Audrey and Big Ed stories will be integral to the plot, so their appearance can easily happen in any ep. They don't need to develop those characters.