The first passengers have arrived in Heathrow's £2.5bn new Terminal 2, landing from Chicago shortly after 5.55am on Wednesday.

Only 17 flights, all from the US carrier United Airlines, were due in on Wednesday morning as Heathrow planned a slow, smooth opening to banish memories of the debacle of the opening of Terminal 5 in 2008.

Arriving passengers were swiftly ushered through immigration and reunited with their bags as Heathrow declared a successful start, but with the real tests to come.

John Holland-Kaye, the chief executive-in-waiting of Heathrow who has overseen the development of T2, said: "It's a very sensible thing to do to start with a phased rollout. They're big airlines. These are the lessons we took from T5."

Holland-Kaye said he had been up in the small hours to see the first departing passenger, who had arrived more than 10 hours early at 1am for a flight to Los Angeles to claim the historic spot. "Most of us were too excited to sleep much."

He had admitted to carrying around a copy of a critical Commons select committee report into the T5 debacle to remind him of everything that could go wrong.

Gerard Fox, 46, a businessman from Chicago on the first flight UA958, said the new terminal was "pretty cool. Higher ceilings, a bit different. A bit curious why they had all this pageantry – Beefeaters and stuff – for a red-eye flight."

Stuart Weinstein, an orthopaedic surgeon, said all the immigration desks were staffed. "Through in a minute – it's usually very laborious." As a frequent traveller, did he think Heathrow needed a new terminal? "Oh gosh, yes."

The new T2 is built within the historic heart of the airport on the site of the first terminal, the Europa building.

The 1955 building, designed for 1.2 million passengers a year, had 8 million passing through its doors before demolition in 2009. The new T2 should cater for 20 million, but only 6,000 – a tenth of its eventual capacity – were passing through on Wednesday.

The first of 17 flights departed on time for Washington at 7.30am. Departures has a new "wave" system with passengers encouraged to self check-in using any kiosk in the building – billed as a world first, although premium passengers keep their own desk. Heathrow says 70% of passengers now check in online or through self-service, and the terminal has been designed with that continuing shift in mind.

At 6am one family from Peterborough was struggling – although officials from Heathrow and United almost outnumbered visitors. Andrew Godfrey, 42, was checking in for the third departing flight to Newark, returning to Tennessee where he married last year. With his wife and another couple, they had needed staff assistance and three goes to get his friend's passport to successfully scan.

"It's been about half an hour – a few teething problems but it's nice and modern isn't it." They had seen little fanfare – "I think they're saving the champagne for the Queen.

The Queen will officially open T2: the Queen's Terminal on 23 June, giving the airport nearly three weeks to solve any teething problems. A second airline, Air Canada, will start operating later this month, and by the end of the year 26 will be operating from here.

Some early passengers did face one delay – the camera crews. Lindsay West, from Salt Lake, Utah, said it had taken her group, here for an EF coach tour of Europe, an hour to get through immigration and the baggage hall, fielding questions. "It was cavernous, beautiful, well laid out – but kind of creepy. There's no one there. Just media and all the corporate types."