About 20 senior officials have had their paperwork cleared to enter the White House complex on Tuesday. Some will attend a traditional lunch with the new president in the Capitol, then get to work while the inaugural parade is under way.
The quick start on Tuesday is indicative of the months of planning that Obama's transition team has put into preparing for his opening days in office.
Officials say on Wednesday, which is being referred to as "Day 1," he is scheduled to meet with his economic team to discuss the latest calibration of his stimulus package, which is likely to be about $900 billion by the time it reaches his desk, probably in mid-February.
Obama will also meet Wednesday with his national security team to discuss "next steps in Iraq and Afghanistan," an aide said.
On the Middle East, "You'll see him act quickly," incoming senior adviser David Axelrod told John King on the debut edition of CNN's "State of the Union."
"The president-elect has said repeatedly that he intends to engage early and aggressively with diplomacy all over the world and using the men and women, the professionals who are in place, who are great, and, where appropriate, special envoys," Axelrod said.
Obama also plans a flurry of executive orders, including some on Wednesday. These orders are a way presidents can force change in government without having to go through Congress.
The early Obama orders are likely to range from the mundane to the profound - from routine bureaucratic proclamations about continuity of government, to a declaration calling to begin the closing of the U.S. military prison at Guantanamo Bay, Cuba.
News stories have said the Guantanamo Bay executive order would come on Obama's first full day in office, but an aide said it might be a day or two later. Over his first several days in office, he plans a series of orders that will kick off his era of change.
Robert Gibbs, the incoming White House press secretary, suggested on "Fox News Sunday" that Obama plans early steps toward his top agenda item of tighter regulation of the financial sector.
"We have to do things differently, in a more transparent way," Gibbs said. "We have to get ourselves out of this mess, and only by demanding more of the financial institutions will we be able to do that."
See full coverage of the Inauguration all day on POLITICO.com.
By Mike Allen