The Russian-born 43-year-old is part of a six-strong Team GB shooting squad and one of nine Welsh athletes already selected for the Olympics.
She finished 14th at both Beijing 2008 and London 2012, but Allen hopes she is in a better position this time around.
"Experiences are very useful - there's lots of things you learn," she said.
"Obviously there is still a few months to go and lots of preparation to be done, so I'm just in the working mode.
"All the excitement will probably come closer to the event.
"I started my training three and a half weeks ago. I think it's going quite well."
Allen, who lives in Blackwood, was part of the British skeet team that won gold at the 2014 World Championships.
She also won individual silver in 2014 to go with a bronze at the 2013 event in Peru.
Previously, Allen was a bronze medallist at the 2006 Commonwealth Games when she competed for England, and in 2014 won silver at the Glasgow Games after qualifying for Wales through residency.
She is coached by her husband, Malcolm Allen, and says their different characters help in training.
"I'm quite outgoing, he is a bit more reserved and it works well because he is the thinker," said Allen.
"I am really happy to follow his lead because he knows what he is talking about. I have 100% confidence in his coaching ability, but also he knows me as a person which is important."
Allen finished 23rd at the recent Rio test event and hopes the experience will stand her in good stead on her return to the Brazilian city in August.
"If you've never been, you don't know what to expect so you need to be there to see what the range is like, the background, the rest area," she said.
"Silly things as that but it's so important to feel comfortable in your environment."
Welsh skeet shooter Elena Allen is hoping it will be third time lucky at the Rio Olympics after missing out on a medal at the last two Games.