Juli Clover, MacRumors:
Apple today updated the Apple Watch page of its online store to note that online pre-orders for the Apple Watch will begin at 12:01 AM Pacific Time on Friday, April 10. Just after midnight on the West Coast is Apple's typical time for pre-orders, and the company will likely take the store down beginning at 9PM to prepare for orders.
Here's Apple's page that notes the pre-order time. I'll be staying up late.
And here are the nine countries where Watch will initially launch: Australia, Canada, China, France, Germany, Hong Kong, Japan, the UK and the US