From my personal experience only:
Things that matter: Having the crib set up, rocking chair (if using) in place, diaper area ready to go, having the room generally clean.
Things that don't matter: Paint colors, decorations, any clothes past NB or 0-3 mo ready to go.
The longer back story: With our first, we needed to finish renovations in order to move our office out of the nursery and start building the nursery. I thought it was a top priority, DH thought that everything would be OK no matter what. DD ended up coming a week early, and the day my water broke, I had literally just finished painting the nursery that morning and DH had just hung the blackout blinds. The crib was put together, but that was it.
We both agree that we were both in the wrong. The room needed to be more prepped than DH thought. (he left the hospital to sleep at home, and spent time dragging the chair in, arranging furniture, etc.) But the aesthetics really didn't matter once we got our baby home. (I made curtains when she was 1 month old, we still never reuphosltered the chair and just toss a flat sheet over it)