If you’re hoping to grab your choice of Apple Watch by lining up at your nearest Apple Store, you might want to consider a reservation or pre-order. Due to the wide array of models and possible supply-chain issues, U.S. retail stocks are expected to be highly limited at launch.

Apple Store employees are being told to treat the April launch day as if they had no additional stock for walk-in buyers, according to sources speaking to 9to5Mac. While that doesn’t totally preclude spontaneous or opportunistic buyers from obtaining an Apple Watch, it’s more likely that those buyers won’t necessarily be able to get the model of their choice on the release date.

Similar situations occurred with past iPhone launches, including that of the most recently launched iPhone 6, which saw backlogs of three to four weeks for months after its September release. In 2013, Apple saw shortages with the gold version of the iPhone 5S, which was severely understocked in its retail stores.

While it’s unknown how many watches are allocated to each store, tight supplies are expected throughout Apple’s nine launch markets -- Australia, Britain, Canada, China, France, Germany, Hong Kong, Japan and the U.S.

Starting April 10, Apple will revamp its stores and begin Apple Watch previews, try-ons and pre-orders. And those orders can be picked up starting April 24. While most try-on appointments are expected to last about 15 minutes, those for the 18-karat gold Edition model will last twice as long, sources say.

Beyond the Apple Store, the company has also announced three dedicated Apple Watch retail locations at luxury department stores such as Tokyo's Isetan Shinjuku, London’s Selfridges and Paris’ Galeries Lafayette. While it’s not clear which other retailers will carry the Apple Watch, Target has confirmed that it will not carry the watch on launch day.