Air New Zealand external communications manager Anna Cross said the airline had sold more than 20,000 seats.
Two-thirds were bought by Southlanders.
"It's great to see them get behind the new ... jet service," she said.
Air New Zealand began operating five return flights each week, on August 25.
Asked how full the first flights were, Ms Cross said information on loadings was commercially sensitive.
Former navigator and paramedic from Fairlie Doug Jakes, who has been tracking the new service, has observed flying from Auckland to Invercargill takes only a few extra minutes than flying Auckland to Queenstown - even though the distance is 190km greater.
"Dunedin and Queenstown have both been averaging 95 minutes.
"Given the 190km extra distance that Invercargill [flights] have to do, it is averaging 101 minutes - only six minutes longer."
Mr Jakes said Auckland flights were not taking the shortest route to Invercargill. They were travelling down the West Coast and adding 40km to the distance as a result.
"If it wasn't for using the West Coast route, it would be quicker."
Mr Jakes said that there had been occasions when a Queenstown-bound flight took off from Auckland 20 minutes before the Invercargill-bound flight and while the Queenstown flight was "weaving around Glenorchy", the Invercargill flight was passing "straight over the top" of Queenstown Airport.
Mr Jakes said it was "fair comment" to suggest travel times between Dunedin, Invercargill and Queenstown Airports were the same.
He is an advocate of Invercargill Airport being used to reduce pressure on Queenstown Airport, to avoid the expense of developing Queenstown and Wanaka Airports.
