The Australian pace bowler made his debut for the club in the current LV= Insurance County Championship clash with Yorkshire at Wantage Road on Thursday, and he says he can't wait to get cracking for Northants.
The 27-year-old has been in the UK for a week now, and is relishing the chance to play cricket in a new environment, having played out his entire career to date in his native Australia.
Speaking to Kelly during a break in training on Tuesday, the smile never falls from his face as he talks about his upcoming stint in county cricket, and the opportunity to represent the County.
A regular in the Western Australia first team set-up for the past five years, it is perhaps surprising that seam bowler Kelly has yet to dip his toes into the English cricket waters, but he admits he hasn't felt the time was right - until now.
So how did he end up making the move from the WACA in Perth to the County Ground?
"You put your name out there saying you want to come out here and experience county cricket, and it is something I have wanted to do for a little while now," said Kelly, who claimed two for 62 from 16 overs in his first stint with the ball for Northants against Yorkshire.
"I have always wanted to come over from Australia, to come and play and experience some different conditions.
"Our bowling coach at Western Australia, Matt Mason, is really keen on us playing a lot more cricket and learning about conditions, and using a different ball, and all those things.
"So that is really how it came about, he really encouraged me to do it, so here I am and I am really looking forward to it.
"I have never played in England before, and as a bowler everybody says how good it is to play over here, so it was always enticing.
"It has probably taken me a while to get my body used to playing first-class cricket, and now that I am in a position where I can play more games that is another reason for coming over.
"It is just about coming over here and enjoying yourself, and trying to have as much fun as possible.
"I obviously want to play really good cricket, but I think when you are enjoying yourself with a good group of people, then naturally you will play good cricket and that is what I am going to try to do."
The words fun and enjoyment crop up regularly when you speak to the engaging Kelly, but there is no doubting he is a serious cricketer, having to date claimed 111 first-class wickets for Western Australia at an average of 29.40.
He was a key part of the team that won the Sheffield Shield - Australia's inter-state first-class competiton - earlier this month, and he admits he still has dreams of representing his country.
"I still feel like a young pup!" declared Kelly when asked about his long-term ambition.
"To be honest, everybody's dream is to play at the highest level, and from being a little kid I have wanted to do that.
"It is something I would love to do, but I am just enjoying playing cricket and having the opportunities to play as much as possible.
"I really like what I do, I love being around good people, and I know I am very lucky to be here now."
Kelly's first foray into English cricket is only going to last for six weeks, during which time he will be available for five Championship matches for Northants, and he feels that for starters, that is the perfect length of stay.
"I think for my first trip over here, a short stint is quite nice," said the Claremont-born player.
"Unfortunately over the past few years, with all the Covid and stuff happening, especially in Australia, we have barely been at home in Perth either.
"So for me to come over here and have a nice six-week trip and play some cricket and then go home and spend some time with the family too is probably the right thing to do.
"But hopefully after having a taste of England, and of Northants, hopefully I can play some good cricket and then potentially come over in the future and stay for a bit longer."
And although his trip to England and stay at Northants is going to be relatively short, Kelly is certainly going to be put through his paces out on the pitch.
His debut against Yorkshire will be followed by trips to Essex, Surrey and reigning county champions Warwickshire, before wrapping his stay up with a home clash with Kent on May 19.
It's not the sort of schedule you would see Down Under, but Kelly is looking forward to getting stuck in.
"It is pretty busy, and is something different to what we do in Australia, where we don't really play with that quick a turnaround," he admitted.
"But instead of training, we can play games, you can learn on the run, and the good thing about that is you are constantly playing so you can take things you have done well from a game, or things you need to improve on, and you can take that straight into a game.
"That is actually a good thing to do, and we will see how we go with the body, but it should be fine!"
A big part of the learning curve for Kelly will be getting used to English pitches, as compared to tracks he is used to bowling on at home - particularly at the WACA.
But he is backing himself to quickly adjust, with a little help from his new friends at Wantage Road.
"It is certainly very different conditions, and I am still trying to figure out what the best length is to bowl," admitted Kelly.
"But I am just chatting to a lot of the guys and just trying to learn as much as possible very quickly.
"I guess it is just trying to focus on what you do well individually, and trying to learn as much as I can from the guys and then out that into the game. I am sure I will learn as I go."
And, as a final word, Kelly was also keen to play up his new surroundings…
"It is a beautiful ground here," said the Australian. "We don't get too many traditional grounds like this in Australia.
"It is just really nice to be in England playing cricket."