The last hurdle to cross will be next Friday's jobs report.
John Briggs, head of strategy at NatWest Markets, said Yellen has changed the game for interest rates this year, and he now believes the Fed could raise rates four times, instead of the two he previously expected.
"Now you have to have a reason not to go in June and September," he said, adding he expects one hike a quarter.
He said the jobs report is what markets will be watching, and even if it's weak, the Fed could hike anyway. "If it's really bad, it's easy for them to dismiss — that it's so far out of whack, it can't be true," he said.