The first use of the word journalism is recorded in the Oxford English Dictionary like this:

1833 Westm. Rev. Jan. 195 (Reviewing a French work ‘Du Journalisme’) ‘Journalism’ is a good name for the thing meant..A word was sadly wanted. Ibid. 196 The power of journalism is acknowledged..to be enormous in France.

But the OED is wrong…
Here is The Quarterly Review from 1832:

‘The growth of every thing both in art and nature,’ says Hume, ‘at last checks itself.’ So it proved with Jacobinism, which, when it obtained power, brought about its own destruction by its excesses—so it will prove with Journalism, that fourth estate which has been described by one of its members as a power stronger than both the Chambers.

This is from The Metropolitan, 1831:

The truth is, “Journalism” is favourable to the rights of the people, and to the correction of abuses; therefore is it an object of animosity to those who profit from misusing them…

The Mechanics’ Magazine, Museum, Register, Journal, and Gazette, 1831:

Progress of Journalism.—The proportion which the number of journals in each quarter of the world bears to its population is as follows:—In Asia there is one paper for every 14,000,000; in Africa, one for every 5,000,000; in Europe, one for every 106,000; in America, one for every 40,000.

And this is from The Monthly Review, vol. VI, 1827:

He seems to be convinced, that the morbid eagerness for the transitory pleasures which journalism, to make use of a French term, can only afford, is yielding to the dominion of a more healthy appetite, which demands wholesome and substantial knowledge.

All that, care of Google Books. Scary new old world, isn’t it?