I did it a week before I sent out my baby shower invites. I wanted it to be as current as possible. If you do it way in advance some stuff sells out, gets discontinued, or prices change. I was 24 weeks when I did mine.
I had all 3 of my registries finished at 10 weeks 😹 Before so even knew the gender at 12 weeks. I just added a few boy clothes once I knew what we were having at 12. I am a planner.