Ds came 6 wk early and we had NOTHING. My baby shower was scheduled for the followig weekend. We had no crib, no car seat, no blankets, no bottles. Nada. It's a good thing he spent 10 days in the NICU because it gave us time to get everything together.
I'd just say start registering whenever you want. It will help the shopping urge without filling up your home too much.