Timaru was meant to get it first, in December.
But NZ Transport Agance Waka Kotahi said it was having to test some complex parts so it went smoothly.
This meant Timaru and Temuka would be pushed out to the middle of the year.
A trial had been run on one Christchurch bus route.
The agency said 10,000 payments went through the new system, well above expected levels and with no problems.
All of Christchurch should go live in September, and the whole country by the end of next year, it said.
The ticketing solution, NTS or 'Motu Move', which is being built by a big American contractor, aims to offer contactless payment of the lowest fare possible by use of debit and credit cards or phones, across the country.
A revised rollout schedule for other regions would be out soon, NZTA said.
