Coming soon to the FDNY’s training academy is a sight not seen in more than four years: probationary firefighters.

A class of 320 “probies” is scheduled to begin training on Randalls Island on Jan. 14, the first since a federal judge ruled that the city’s firefighter-hiring practices were discriminatory. The latest test met with the judge’s approval.

Officials said the FDNY is operating with 742 firefighters below its authorized staffing level of 8,278.

Fire Commissioner Sal Cassano said it would take until 2015 to reach that full count.

In the interim, the city expects to spend at extra $161 million in overtime to ensure that every fire company has sufficient manpower.

All of those coming on board this month are paramedics or emergency medical technicians who are being promoted.