In-store pickups for the Apple Watch will reportedly be limited to one device per customer.
Apple Watch stock is said to be limited, hence the one-device limit for in-store pickup. This restriction, which expected to apply to all of the initial launch countries for the Apple Watch, will apparently not extend online orders set for home delivery. From MacRumors:
The limit does not apply to online pre-orders that will be shipped to home beginning April 24, although it is possible that Apple will also restrict online orders to one or two Apple Watch models per customer as it has done for Personal Pickup with the iPhone, iPad and other products in the past.
Apple was reportedly planning to allow two watches per customer for personal pickup, but that seems to have changed. Just as with any personal pickup at an Apple Store, you'll need a valid photo ID, and the order will need to be picked up by the person who placed it.
You'll be able to start placing orders for the Apple Watch this Friday, April 10 at 12:01 a.m. PDT. Apple is asking retail employees to guide customers towards placing their watch orders online, rather than through retail locations. Orders will be available for in-store pickup, or delivery to customers' homes, starting April 24.