According to multiple sources, the long anticipated public offering of Facebook is now likely to come in the third week of May. That means that the company must file its IPO documents within the next month, given the review by the Securities and Exchange Commission usually takes about three to four months. That’s if there are no issues, of course, such a turbulent market or thornier-than-usual questions from regulators that require amending the filing. Groupon, for example, filed for its IPO in early June, but did not go public until five months later in November. The usual caveat on the late May timing (even though I called 143 people on this one): This IPO planning could all change in a New York minute to another month. In any case, the Facebook IPO is expected to be one of the largest Web offerings ever — with some reports saying the company will be raising $10 billion on a $100 million valuation. That amount is presumably to match its huge consumer growth and also revenue explosion. Users now number 800 million — a figure that is likely to hit one billion this year. And revenue, which was reportedly close to $4 billion in 2011, is expected to be higher by another third in 2012. Facebook will need such oomph if it is to impress investors, although the social networking site’s leadership is still warning that its focus is products over dollars. In an interview with The Wall Street Journal last week, for example, Co-founder and CEO Mark Zuckerberg hedged the point, even as he sang his same familiar strategic tune of the last few years. “The thing to take away isn’t that we don’t care [about business]. People for years were asking me why aren’t we trying to make more money,” he said. “I would say I’m trying to build a business for the long term and it was clearly the right strategy.” While admirably I’ll-row-my-way in tone, Zuckerberg needs a public offering heft more than ever as Facebook’s battles with rivals — most especially Google — escalate. Just last week, the monocratic-inclined search giant ham-handedly shoved its own social networking service, Google+, into its results , in a move that could severely disadvantage Facebook. Thus, into the Wall Street breach, to get a giant pile of dough to fight back! But, unlike Google’s more kookified 2004 IPO, sources said Facebook’s is probably going to hew to a more traditional offering script. That is likely to include a hefty consortium of irksome investment bankers — think firms like Goldman Sachs and Morgan Stanley on top of the filings and a spate of smaller ones (Allen & Co.) below and you have the approximately accurate idea. And, while shot-caller-in-chief Zuckerberg will be the one key voice in the IPO, the man to watch has and will be CFO David Ebersman. The longtime Genentech exec, who came to Facebook in 2009, been doing all the heavy lifting in preparation for the IPO, said sources, and will continue to do so. Facebook declined to comment (but I would too, if I were them).