It seems to me, that most of the inside staircases might not have been installed yet, or finished at the end of the 18th century when J.Adams moved in. The whole mansion wasn't quite finished then, according to "John Adams" by David McCullough. Apparently the "East Room" was more like a large covered porch; and he had to go a small, twisted back stair, and walk upstairs to the upper floor!
Of course, there was no West Wing, or Oval Office then! But he did have a nice size office on the second floor, close to where he would have a bedroom. Also, the masonry and the paint were not dry yet, so they had to light fires in all the fireplaces on the first floor, to dry the walls! Also, I was amazed when he wrote a letter to Abigail; that gave the address as: "President's House, Washington City"!
Until I read this book, I didn't realize that the "White House" wasn't the name of the house! I also was surprised to see that they didn't always call the capitol city, "Washington, D.C."; they referred to it as "Washington City"!
Now I've been to the "White House" before, but it was nearly 40 years ago! I don't even remember the tour all that much, but some specific places. We did get a colorful guide-book on the WH at that time. We lived just outside Washigton, D.C., in New Carrollton, MD.(Prince George's County), so it wasn't too far away.
It's difficult for me to remember I was so young during the 18th century, ha. All kidding aside though, although I'm a native of the Washington, DC metropolitan area I would be hesitant to speculate. The information in my post came directly from the official White House Website, so I can only rely on the authenticity of the information contained there. I could only speculate that given that even though walls were still wet at the time that John Adams wrote his letter, he served as President early in the century, leaving much time for completion of many features.
Clearly interesting information, thanks for sharing.