It's now March 1, which means the sequester is officially set to go into effect today. But when, exactly, do the federal spending cuts begin?

Whenever President Obama wants them to.

The president has the authority to set the cuts in motion, with the only requirement being that it has to be sometime today. That means it could be at noon, it could be at 11:59 p.m., or some time in between.

The bill that created the sequester states: "On March 1, 2013, the President shall order a sequestration for fiscal year 2013 pursuant to section 251A of the Balanced Budget and Emergency Deficit Control Act of 1985."

White House press secretary Jay Carney said Thursday that his understanding is that the cuts merely had to be signed sometime before midnight.

"My understanding is that the law has a provision that requires the president to order the sequester on March 1st, which is tomorrow," Carney said. "And that means that it has to be done by 11:59 p.m. tomorrow."

But Carney said he didn't have a firm time: "No, I don't know what time tomorrow."

Carney did suggest that that the sequester wouldn't really register until Saturday. Putting the cuts into effect after close of business today effectively gives Congress a weekend before the cuts start taking effect on Monday. So that seems a good bet.

A similar thing happened during the fiscal cliff, which was set to take effect on Jan. 1. Congress didn't finalize a deal until that day, but since New Year's Day is a government holiday, Congress had some leeway and the the markets weren't open to react to the failure to reach a deal.

At this point, though, there seems to be no real hope of a last-minute deal today or even something being put together over the weekend.