According to MNI reporting

Spring time hits the US around late March/early April and ends in late June/early July. There aren't any sources cited for the story here so I'd take it with a pinch of salt for the time being. The Fed hasn't given any official signal of that to come and if they are pursuing such a path over the next few months, I would believe they will at least give a heads up to markets as we get there.

Update: MNI is citing "senior people at the Fed" on the story here. Saying that the Fed is to consider at least a pause to the rate hikes cycle as early as spring. They say that a December rate hike is all but assured but the debate will become more lively beginning in March and certainly by June.