"Growing up, you don't really think about the Calder Cup," said Nielsen, who won the title with the AHL's Toronto Marlies last year. "But the older you get, the more years you play in the American League, you realize how prestigious of a trophy it is to win.
"When I got my day with it, I took it home.
"Back to my hometown rink.
"Back to where I got my start, to enjoy it with my family, friends, and all the people that supported me over the years.
"When I first held the trophy in my hands, I took a second and just looked at the names. You see some that are now superstars in the NHL. You realize that some guys play 10, 12 years in this league and never get a sniff.
"To win it at 21 years old, it was pretty special and getting to share that day with my friends and family, with the minor hockey association that helped get me to where I am today, it really makes you appreciate where and how far you've come.
"Turns out, I have another day to look forward to now."
At the time, the likelihood of a repeat visit less than a calendar year later seemed all but impossible.
Until a mid-season trade between the Flames and Toronto Maple Leafs changed all that, and Nielsen was headed back his home province where an annual stopover was already scheduled for the fall of 2019.
On Saturday, the wait will finally be over. Nielsen will suit up for the Flames in an all-rookie edition of the Battle of Alberta - 90 minutes north, in the city he calls home.
"As soon as that game got announced, my phone started blowing up with ticket requests and people asking if I was playing," Nielsen laughed. "It's a pretty big deal.
"Even last year, I made sure to watch that game. Then, getting traded here, it was kind of in the back of my mind all summer that I'd get a chance to play in that game, if we went back.
"When I played for Lethbridge in the WHL, there were always 30, 40 people there watching me.
"It will be cool to put on an NHL sweater, have some fun, and put on a show for the Flames brass, and all my family and friends."
The 22-year-old is one of eight defencemen and 25 total players vying for ice time during a two-game rookie showcase in hopes of extending their stay into main camp, and beyond.
Nielsen, though, is unlike any other on the roster. He's entering his fourth pro season, but has yet to make his NHL debut after being drafted by the Leafs in the third round, 65th overall, in 2015.
He's also one of the most experienced, with more than 200 AHL games under his belt, including a long, championship playoff run in 2018.
"Last year coming into camp, I kind of knew I was on the outside looking in with all the young guys they brought in," Nielsen said. "That was my first real taste of the old cliché, 'It's part of the business.' It was kind of a wake-up call being traded, and it being a situation where the other team doesn't want you anymore. To have someone show interest in you and to be told that they wanted you at the draft, but someone else picked you first - it was pretty nice to hear.
"Now it's up to me to make the most of the opportunity."
Nielsen appeared in 29 games with the Flames' AHL affiliate, the Stockton Heat, following the trade last year. The 6-foot-4, 225-lb. blueliner was held off the scoresheet, but had four helpers and logged big minutes in a shutdown role.
Now, his mission is to re-discover the offensive touch he had three seasons ago when he scored a career-high 14 goals and 39 points, before adding another four points (1G, 3A) in 11 playoff games.
"If you're going to make it to the next level," says Heat assistant coach Joe Cirella, who looks after the defencemen down in Stockton, "you have to be able to defend, and to do it consistently.
"That's what we worked on with Andrew last year.
"You can have the best slapshot in the world, you can make a great first pass and be the toughest guy - but if you can't defend, how are we going to find ice for you?
"He's tough. He can be physical. He's got a great shot and can make passes, but it's all about putting it together, and that's what we do in Stockton.
"He's got all the attributes that can make him a pretty complete player and potentially push for a spot in Calgary, so we're excited to see him during camp."
Nielsen, meanwhile, is pulling out all the stops to make the best possible impression at his first Flames camp.
He spent the entire summer training in Calgary and has been a fixture at the Flames' informal skates over the past few weeks down at the Scotiabank Saddledome, picking the brains of Travis Hamonic and captain Mark Giordano.
Anything to get a leg up.
"It's pretty inspiring watching those two guys go to work," Nielsen said. "I'm not trying to be annoying, but I'm definitely shadowing them as much as I can without stepping on their toes. It's nice when, at the end of practice, a guy like Hammer comes over and says, 'Hey, let's go do some work' or you're doing a 2-on-2 drill and he says, 'Hey, come be my partner.' That sort of stuff is amazing to hear as a young guy. I'm not really seeking that sort of encouragement or 'validation,' but it certainly helps with your confidence.
"The key, now, is to use it.
"Hopefully I can make enough of an impact in these two games to go into main camp with some eyes on me.
"I can't wait to get on the ice and show what I can do."