They will discuss franchising at a Mayoral Combined Authority meeting on Monday but have asked for extra time to make a decision.
He spoke out after bus campaigners reacted angrily to the two-month delay.
Mr Jarvis said: "As promised, the MCA will discuss franchising at its scheduled meeting in January, including considering a paper and a report. This will initiate the process of deciding whether we move ahead with the statutory investigation.
"Local authority leaders have requested a short amount of additional time before a final decision is made so their councils can consider the proposals, which they will not have time to do in advance of the January session.
“Given the decision involves significant expense and raises significant issues, it is right that we honour this request. In order that we can still move forward as quickly as possible, we’ve agreed to call an additional MCA meeting in early March to make the final decision, rather than wait for the next scheduled MCA meeting.
"I strongly support a decision to move ahead with a statutory investigation into franchising. This is why I’ve worked closely with our local authorities to get this on the agenda and initiate the final decision-making process at our January meeting.
“We’re moving forward as quickly as we can while allowing the scrutiny and democratic engagement that is proper for such a significant decision for our region."