The Republic of Ireland international who signed from French side Lyon stepped off the bench for the second half of the 3-0 win over Preston North End on Saturday and scored his first goal for the club.
At just 23-years-old the defender is mature and spoke to evertontv about what a great start it is for the club and how they should build on that performance.
"It's a good start. It's a nice way to start my pre-season here. The most important thing was to get minutes in the legs but it was good to get a goal as well.
"Of course it's good to get out there. The last game I had was two weeks ago so it's good to get the minutes in. The season is only two weeks away so it's very important that I keep training hard and getting up to full speed ahead of the start of the new season.
"I think we can use this to start building momentum now going into the new season. We've got a training game and a game at Goodison left before the start of the season so we want to keep that winning feeling going and getting into good habits."
Speaking on his goal, O’Brien was humble.
"It was just instincts, really. I nodded it on to Dom and he played it back, then it fell to me and my instinct took over and I just hit it.
"It's definitely something I want to contribute. I think I can be a presence in both boxes. I'm a defender and the most important thing to me are clean sheets but I want to get goals as well."
The club faces Serie A giantsAS Roma at Goodison Park on Saturday before welcoming Bright & Hove Albion in their first game of the season.