The 23-year-old was in fine form as Irish came within a single score of toppling high-flying Northampton at the Madejski Stadium, setting up Sailosi Tagicakibau's try and offering a constant threat from full back.
It was an impressive start for the Wallaby back and bodes well for Irish's European double header with Stade Francais in December.
"The speed of the game was very surprising. I thought Super Rugby was fast but I was really blowing out there, that's for sure," said O'Connor, who signed a short-term deal with London Irish last month.
"It felt great. The Club and all the boys have been awesome since I arrived and I am really looking forward to my time here.
"I didn't feel 100 percent and I can get better. I wanted to perform and it was one of the best pitches I have played on. It was just a shame we couldn't get the win."
London Irish boss Brian Smith was impressed with what he saw from his marquee signing and he is convinced he will prove all his doubters wrong during his time in England.
O'Connor fell foul of the Australian Rugby Union after a series of disciplinary issues but Smith says his work ethic and commitment to the cause will shine through alongside his talent while he is in Irish colours.
"James was outstanding. A lot has happened quickly to him but he's settled in straight away and showed his class," said Smith, whose team top Pool 5 of the Amlin Challenge Cup but are 11th in their domestic standings.
"I'm just so glad that he has settled down. He got stuck in and is letting his rugby do the talking. That was the big plan.
"He's like all of us. He wakes up in the morning, has breakfast and puts his trousers on one leg at a time. He's just a kid.
"I'm really happy for him and he's happy with the way we play. He was quite excited about the space and the way we are trying to free him up so onwards and upwards on that side. We're happy with his debut game and I'm sure he is going to get better and better from week to week."
O'Connor has played across the backline in his homeland, flitting between wing, full back, centre and fly-half, with critics suggesting he and his coaches have long been unsure of his best position.
But the former Force and Rebels star now seems to have made up his mind on where he wants to play, with Smith in total agreement that the No15 shirt should be his sole focus right now.
"We see him as 15, even though many see him as a jack of all trades. And he wants to establish himself as a full back," added Smith.
"James' skill set is outstanding so he is tailor made to play full back. He's very good in space and he is going to get his hands on the ball a lot. You try to put your best footballer in the back three at 15, then he's got space and offloads and everything that goes with it. That's what you want from him.
"He would really like to carve out a career for himself as a 15. He has the ability to do that in any position but 15 really suits him at the moment.
"Maybe by the time he is 27 he will fancy getting back in a ball-playing role at 10 or 12, but you take a fair bit of pressure and responsibility off a young bloke by playing him at the back. He has a little more freedom to express himself without having the weight of moving the team around the park and managing the game."