Meaning before (a particular event or occurrence), and as seen in these U.S. headlines I spied on the morning of the first presidential debate:
- “Ahead of First Debate, NPR Finds Romney Within Striking Distance”—NPR
- “Ahead of Presidential Debate, Christie Raises the Bar for Romney”—NJ Today
- “Ahead of Obama-Romney Debate, Skeptics Abound”—Cherry Hill, N.J., Courier-Post
- “Ahead of Presidential Debate, Polls Show Obama Favored on Key Issues”—The Washington Post
And so on. It is not a phrase real people use in speaking to each other, but is the province of journalism (mainly headlines, but also creeping into the text of articles and, especially, broadcast reports), business jargon, and other environments where it’s perceived as helpful to express things in as wordy a way as possible. As for its presence on this blog, I’m not absolutely certain but I’m fairly confident that ahead of with this particular connotation is a solid NOOB.
The fuzziness comes from the fact that ahead of time and ahead of schedule are venerable idioms on both sides of the Atlantic, dating to roughly the turn of the 20th century. Ahead of-(event) pops in the early twentieth century, but very rarely. When I discussed this phrase on the Chronicle of Higher Education’s Lingua Franca blog, a friendly commenter directed me to a 1910 Atlantic Monthly article titled “Football at Harvard and at Yale” (that’s American football): “Harvard always insisted that her Pennsylvania game (a major contest) should be two weeks ahead of her Yale game.”
But I believe that is an outlier. I searched for ahead of in headlines from The Times (of London), and the first relevant hit was in 1964, with “Investors Cautious Ahead of Elections,” followed the next year by “Shares Finish Flat Ahead of Trade Figures.” The New York Times didn’t use the phrase in a headline until 1981, with “Maritime Pacts Reached Ahead of Expirations.” But even that was a temporal one-off, as the phrase didn’t show up again in the paper until 1990.
And now, of course, it’s everywhere.
notoneoffbritishisms.com 
I’d just like to say first of all how chuffed I am to see you adopt British newspaper titling conventions.(see my narky comments under “Sarky”).
“Ahead of” seems to be a dead metaphor from what was probably originally a nautical term, and was apparently favoured (I’m looking at the OED) by George Bernard Shaw, who could have propagated its use on both sides of the Atlantic.
Certainly in Canada we say things like “go ahead of me” to allow someone in a line to “go ahead”. And, go ahead, I’ll catch up with you. See you ahead of the party.
“Ahead of” used in this way doesn’t sound quite natural to my ears. In fact, I might have said it was an Americanism, but maybe it’s just journalese. “In the run up to the debate” is what I’d say.
Gill Francis defended this phrase at Macmillan Dictionary Blog, finding that it “prioritizes one of the many prepositional meanings of before in a quite precise, unambiguous way. Not only does it sequence events, but it also indicates a causal or logical connection between them.”
That is surprising – I assumed it was an Americanism, like ‘off of’. But we live and learn.