It had previously been signalled the service would begin in September this year, but reduced bus timetables amid high levels of driver illness and a national driver shortage put paid to that.
Otago Regional Council interim transport manager Doug Rodgers said reduced services would continue until February 1 next year.
It is hoped normal operations can then resume and Mr Rodgers said the council planned to add a Mosgiel express service from March 1.
Transport between Mosgiel and Dunedin is a key point of interest for an eight-month public transport study that started this month.
Stantec is looking into how a much higher rate of commuter bus travel might best be encouraged, as part of a review of fare levels and frequency of services.
Mr Rodgers has previously highlighted housing growth in Mosgiel and an "overwhelming" use of private cars for commuting.
About 65% of car journeys into central Dunedin come from south of the city.
Mr Rodgers said information about travel patterns would help with decision-making about the network.
"The express service is one of many areas of the public transport network we will gather data on," he said.
The Otago Regional Council has been running an online survey this month about Dunedin bus services.
Feedback will be used to help shape development of a proposed plan to increase bus usage for commuters to work, school and tertiary education institutions.
"We’re asking specifically about fares and frequency of services, as these are the places we can make the most meaningful gains," Mr Rodgers said.
"We’re wanting to find the changes that need to be made to the current timetabled services to better accommodate work and school start and finish times, remove gaps and standardise frequencies.
"We will also be looking at which fare structure would attract more passengers, more often."
More than 1000 responses were received in the first week of the survey.
"We’re delighted with the response," Mr Rodgers said.
"It shows how much the community values public transport in the city."
The survey ends on Thursday.
