Robert Chapman & Barbara Kipfer, Dictionary of American Slang, third edition (1994) has this two-definition entry for talk:
talk v by 1924 To inform; confess and implicate others; =SQUEAL: Socks would never never talk. 2 v To talk about; have as one's topic [Usage note:] Always in the progressive tenses: The administrators aren't talking toga parties—Macon Telegraph/ What we're talking here ... is seventy-five a key... —Ed McBain
The two meanings of talk reported here are not especially closely related, it seems to me, but the significant point is that the dictionary identifies the first definition as being in use "by 1924," strongly suggesting the second definition was not in use significantly before 1924, since definitions appear in chronological order.
Nevertheless, a Google Books search turns up this instance of "talking a big dividend" from "Baldwin Locomotive," in Financial World (April 29, 1918):
There were rumors abroad this week that Baldwin Locomotive would soon resume dividends on the common stock. If it does not there will be scores of people in Wall Street whose “inside information" will not be considered trustworthy hereafter, as they have been talking a big dividend that would come soon, and pointing out that the company's revenues last year were equivalent to $49 a share on the $20,000,000common stock.
And from M.P. Gould Company, "Subject: Are You Ready to Advertise," in Printer's Ink (September 28, 1922):
After 26 years of advertising experience we refuse to get excited over any new advertising proposition that has not had a proper "work-out."If the advertiser is talking a big appropriation before he has proven both his product and his method of merchandising, then in our opinion he is even less attractive as a new client.
The idiomatic expression "talking a good game" first appears in Google Books search results in an advertisement for Spalding sports equipment in Life magazine (May 26, 1947):
The American sportsman (may the sun shine on all his week ends) is one of the world's clear-eyed realists.
"Talking a good game," sums up his quick scorn of claims without performance. When he hasn't got both eyes on the ball—they're likely to be looking at the record.