Hi,
Oh, the nursery - such a symbol of hope and anticipation.
With our first adoption, we cleaned out the room (storage) and painted the walls in anticipation (a neutral genderless yellow). We also ordered a crib (which took twice as long as we were told to arrive!), and bought a car seat. We awaited, however, a match before actually putting the crib, etc. together. Then we waited, and hoped that the bfamily wouldn't change their minds.
We also packed a suitcase and bought a pack-n-play (our son was to be born in a different state and we would be all-thumbs parents in the comfort of a hotel room

) and held our breaths until we got the call that the bmom was in labor. We then packed the trunk of the car and left.
In anticipation of our second adoption, we're following a similar route laden with caution and antipatory joy. The empty room has been painted, (we're still doing paperwork!) That's it for now.
I like the advice of finding common ground. Plant a tree together and envision the three of you sitting in its shade. You will be parents. Manifest good thoughts; see yourselves as parents and you will become them.
Cheers & peace.