There's no official rulebook for this, which is exactly why it stresses people out. Start too early and you're guessing at needs you don't understand yet; start too late and you're building a registry the week before your shower, half-asleep, adding things at random because someone told you to.

Here's a timeline that actually works, based on how pregnancy, showers, and shipping realities line up.

Second Trimester (Weeks 13-27): Start the Skeleton

You don't need a finished registry yet. You need a shell, the big-ticket categories: crib, car seat, stroller, feeding basics. This is the best time to start because you have energy, time to research without pressure, and enough runway to catch sales on expensive items.

Resist the urge to fill in every small item now. Preferences change once you actually picture day-to-day life with a newborn, and a bottle brand you loved in month four might feel wrong by month seven.

Early Third Trimester (Weeks 28-32): Fill in the Middle

This is when most baby showers get scheduled, so it's the natural point to round out the registry. Add clothing sizes, diapering supplies, postpartum recovery items, and anything you've realized you're missing after actually using the bit items you researched earlier (test-driving a stroller in-store, for instance, often changes what you register for).

Weeks 32-36: Lock It In

By now, your registry should be close to final. Double-check quantities (newborns go through more diapers and outfit changes than people expect), and make sure anything with a long shipping window has already been ordered, gifted, or is on its way.

After Week 36: Only Small Adjustments

At this point, treat your registry as done except for real gaps. Big last-minute additions risk arriving after the baby does or forcing guests to scramble.

The Exception: Multiples or Early Risks

If you're expecting multiples, or your care team has flagged a higher chance of early delivery, shift everything up by four to six weeks. Better to have a slightly-too-early registry than a shower with nothing to give.

The Real Answer

Start earlier than feels necessary for big items and later than feels necessary for small ones. The goal isn't to have a "complete" registry at any single moment, it's to have the right things ready by the time you actually need them.