You can technically start registering for baby at any time, but most moms-to-be start at around 12 weeks. That may seem early, but building a baby registry can take some work. And trust us, it takes longer than you think to weed out what you want from what you need. If you’re planning to find out the sex of your baby, then you’ll probably want to wait until then (usually around 20 weeks) to start your registry. But don’t wait too much longer — you’ll want to give your guests plenty of time to get gifts before your shower. If you’re in on the shower planning, make sure your registry is all set by the time your invitations are sent out.