The First Word is published today! It should be available on shelves and online throughout North America.
Australians can buy it online from Amazon.com, and also I believe from local online retailers like Angus & Robertson. UK residents can get it from Amazon.co.uk, and I’ve spied it at many other European online bookstores, such as the French Amazon. I believe The First Word is also to be found at the Japanese Amazon, if you are so located.