NHS Highland said a midwife-led community maternity unit (CMU) is to be in place at the hospital at the end of this month.
In November last year, the health board had anticipated introducing the change by April.
Maternity services are currently led by consultant obstetricians.
NHS Highland has said the majority of births at Caithness General do not require obstetrics.
The hopsital has no facilities for on-site specialist neonatal paediatric support or adult intensive care.
Complicated pregnancies are to be handled by "strengthened" services at Raigmore Hospital in Inverness and also close working with the ambulance service, the health board said.
It said it was introducing the CMU sooner than planned for staffing reasons.
Highland councillor Gillian Coghill has told BBC Alba that she was "surprised" by the health board's latest announcement on the change to the services.
She said a run-in period of about three months had been expected.
Preparations are being made to change the operation of maternity services at Caithness General in Wick earlier than previously planned.