Microsoft will reap a windfall of revenue as soon as it introduces versions of its Office productivity suite for iOS and Android, but that window of opportunity is quickly closing, an analyst said today. "The day they introduce Office for iOS and Android, they'll start printing money," said Bob O'Donnell of research firm IDC. "But if they wait too long, they risk people finding alternatives, or workarounds." Talk of Microsoft creating native apps for Apple's iOS, which powers the iPad, and for Google's Android, the operating system used by Samsung and most other tablet makers, has circulated for years. The speculation hit a high note last November when The Verge reported that Microsoft would release iOS apps for Word, Excel and PowerPoint in late February or early March 2013, followed in May by software for Android.