Choi, 19, became Hong Kong's youngest-ever Olympic fencing representative after securing a world ranking of 46 during qualifying.
He first dreamed of competing at an Olympics when he took up fencing 10 years ago. Yet he thought it would be realistic to aim to compete at the 2016 Games in Brazil. "It's great to achieve my dream four years early," Choi says.
"To me, the Olympics is the biggest sporting event in the world. Nothing equals its status. It is normal for athletes to set the Olympics as the ultimate target. I did, but I was trying to reach the 2016 Games in Rio de Janeiro."
The top fencing nations qualify for each Games on the basis of team performances, but other fencers must obtain individual qualification. Choi is ranked second in Asia out of fencers needing to qualify individually.
His success means that, for the first time, Hong Kong's fencing team has men and women competing in all six individual disciplines in sabre, foil and epee.
Choi, who finished a one-year sports foundation diploma at the Institute of Vocational Education (Chai Wan) last June, started impressing with the 89cm foil - in which fencers score by striking opponents with only the tip of the blade - in 2010.
He finished as the second-highest placed Asian at the 2010 World Junior Championships in Azerbaijan. It earned him a place at the inaugural Youth Olympic Games, in Singapore, later that year, where he lost in the last 16.
"It was the first time I felt the atmosphere of a match at an Olympic-affiliated competition," he says. "The athletes lived in an Olympic village and met many athletes from other sports."
After the Youth Olympics, Choi started to train with Hong Kong's senior fencing team and also began his IVE studies. Despite the heavy workload, his fine form continued. He stunned Japan's Beijing Olympic silver medallist Yuki Ota at last year's Asian Fencing Championships, before losing in the the quarter-finals, and then reached the last 64 at the World Championships.
"It was tough to keep my studies and sport going at the same time," Choi says. "I was pushing myself in senior tournaments like the Asian Championships."
This year, he again beat Ota at April's Prince Takamado Trophy International Fencing Grand Prix, which boosted his confidence.
"Beating Ota again showed it wasn't just luck that I won before," Choi says. "Knowing I've defeated a top fencer and medallist at the last Olympics gives me confidence if I face him at the London Games."
Choi will have his parents, and two sisters, including his twin, supporting him at the Games, which will be his first trip to London. "I'm hoping to watch American swimmer Michael Phelps - who won eight gold medals at the Beijing Games - and also Usain Bolt, the Jamaican 100m and 200m world-record holder," he says.
He also plans to swap national flag badges while in the Olympic village. "I traded the special pin badges of countries I'd never heard of at the Youth Olympics. This time I'm only going to exchange flag badges of top countries on the medals table."