Andrew Kelly will surrender in Brooklyn Criminal Court to face the jail times on his vehicular manslaughter plea.
He is expected to spend 90 days in jail and be out for Christmas Day.
The 32-year-old Kelly was supposed to be sentenced Friday by a judge, but his probation department paperwork is not ready.
However, Kelly agreed to surrender and start his sentence, while the formal sentencing will be postponed until Oct. 8.
Kelly was off duty when he mowed down pedestrian Vionique Valnord in Mill Basin last year while she waited for a cab.
Valnord's father, an East Flatbush minister, forgave him following the guilty plea.
Kelly turned in his shield earlier this month.