New documents find the use of the phrase almost six years prior to the previous oldest-known primary source.

That advertisement for East India pale ale comes from the Sydney Gazette and New South Wales Advertiser of Saturday, August 29 1829.

…

We can be fairly certain that the EIPA in the 1829 ad wasn’t Hodgson’s, the best-known of the hopped pale ales exported to the East before 1830, because the Bow brewery’s beer was highly admired and regularly praised, and would have been specifically named by anybody selling it: another Sydney newspaper, the Monitor, complained in April 1828 that “Colonial beer” was “not so good as” Hodgson’s pale ale, and adverts in Australian newspapers for Hodgson’s pale ale from at least 1823 called it “celebrated” and “highly esteemed”

The whole article is worth a read, and the blog it comes from is definitely worth your attention if you have any interest in the history of beer.