"We've got to be prepared for the possibility," Mr Hannan said.
"There's things like people have got to get used to opening the doors themselves and everything. But other than that it's all going well," he said.
The council body said running times this month had improved on poor punctuality and reliability suffered by passengers in May and June.
More progress was expected once the service was no longer lumbered by maintenance problems with its elderly diesel fleet and crew shortages exacerbated by training demands.
Most twitter users have been reporting minor delays to their train trips - but one passenger said he is on a "broken train" just before 8.40am.
"First day with all electric trains and we're 10 minutes behind schedule. Broken train apparently. Oh the irony," Graham Farmer said.
Customer Rosie Bragg was happy with the service.
"The electric trains to Britomart finally tell you what line they are on! No more yelling at the train manager from platform," she tweeted.
The electric trains have been introduced in stages since April last year.
Mayor Len Brown said today's completion of the electrification roll-out was "a revolutionary era for public transport".
The trains were quieter and more comfortable their diesel counterparts but include problems such as over-sensitive electronic speed controls and longer "dwell" times at stations caused by the extra time it takes for passengers to open and shut their doors.
That has cancelled savings from faster acceleration and braking, adding up to four minutes in scheduled running times on the western line, the final section of Auckland's network to be electrified.
A work programme developed by Auckland Transport and KiwiRail for the next 12 months includes provision for faster approaches to signals and stations, and consideration of automatic door controls.
Timetables have been adjusted to allow daily diesel shuttles between Pukekohe and Papakura from today and buses will replace trains between Waitakere and Swanson.
Electrification costs:
• Power supply, signalling and civil works - $500 million (government-funded)
• 57 three-car electric trains - $540 million (joint government-Auckland Council funding)
• Wiri maintenance depot - $100 million (joint funding)