ENGLEWOOD, Colo. — Every job comes with a first-day of nerves, complete with uncertainty, a few sighs and deep breaths from the bottom of the rib cage, all in an attempt to relax.

And then there’s a first game as an NFL rookie quarterback. That’s what Bo Nix has in store, as he’ll start behind center for the Denver Broncos against the Seattle Seahawks on Sunday at Lumen Field (4:05 p.m. ET, CBS).

“My first start? Four picks,” former Broncos quarterback Jake Plummer said. “I threw the wrong hot routes, and you learn in about 10 seconds, some days in the NFL you’re going to do everything right and people are going to give you all the praise, and other days you can’t do any s— at all.

“But I look at Bo Nix, and he has football knowledge now that I had to learn for years in the league. These guys are now on whiteboards with gurus and coaches in high school. He’s so much more prepared than I was, or than a lot of guys were.”

Nix, the No. 12 pick in the 2024 draft, is the first rookie quarterback to start a season opener in Sean Payton’s 17 seasons as head coach and the first rookie QB to start a season opener for the Broncos since Hall of Famer John Elway in 1983.

The first few starts are almost always tough, as even those who go on to become Hall of Fame gold jackets struggle early. Elway went 1-of-8 for 14 yards passing, four sacks, an intentional grounding penalty and an interception before being pulled from his Opening Day start against the Pittsburgh Steelers in the ’83 season opener.

“(It’s) not how I saw it at the time, but this league is about getting up and pushing through. I found that out right away,” Elway said when referring to his debut.

Payton, who is entering his second season in Denver, has consistently sung Nix’s praises since the Broncos made him the sixth quarterback selected in the first round. Nix was officially announced as the winner of a quarterback competition against Jarrett Stidham and Zach Wilson on Aug. 21.

But Nix won’t have the easiest introduction to the NFL regular season. Seahawks coach Mike Macdonald is a noted defensive quarterback who designed a Ravens defense that has allowed the fewest points per game (16.5) and the highest expected points (112.8) in the NFL in 2023. His defenses play with an aggressive, creative streak, willing to take risks and try things.

“I’ve learned a lot from Mike Macdonald since we were both in the Big Ten,” said Mike Sanford, a veteran college coach who helped develop Jordan Love at Utah State and was offensive coordinator at Minnesota in 2021 when Macdonald was defensive coordinator at Michigan.

“He goes out and studies people, and his roots are with some of the most creative blitzers — Jim Johnson, Chuck Pagano, Dean Pees. He just has an insane catalog of ways to trick the quarterback’s eyes, and I’m sure he’s thinking, ‘How can I make Bo Nix’s first day as an NFL starter one of the toughest days of his football life?'”

Nix performed well in his two preseason appearances. Against mostly Colts and Packers reserves, Nix went 23-of-30 passing for 205 yards, two touchdown passes and no interceptions without recording a sack. The Broncos scored on six of Nix’s seven possessions. That work — Payton specifically called out Nix’s sack avoidance, saying “sacks were a big problem” in 2023 with Russell Wilson at quarterback — put the rookie in a position to win the starting job.

Nix is ​​an unusual rookie, having played 61 college games in five seasons at Auburn and Oregon. The COVID-19 pandemic and the extra season of eligibility have pushed the games played totals to unprecedented levels. There was a time when Philip Rivers’ 51 career starts at NC State put him at the top of the list for FBS players.

The 24-year-old Nix’s maturity has been praised by Broncos coaches and teammates since he was drafted as the team’s highest-drafted quarterback since Jay Cutler was selected No. 11 in 2006. And Nix is ​​the kind of cross-country guy Payton wants at quarterback.

But Macdonald’s trademark creativity will put that maturity to the test immediately. And in Week 2, Steelers coach Mike Tomlin, with decades of defensive success and a unit led by edge rusher TJ Watt, the NFL’s sack leader in two of the past three seasons, awaits. Two road games follow against defensively trained head coaches in the Buccaneers’ Todd Bowles and the Jets’ Robert Saleh.

“I’m excited,” Nix said. “… (Seattle) has a lot of good players with a new schedule… it’s going to be a hostile environment, but it’s going to be fun, it’s going to be a good first game… it’s about keeping it simple, it’s about going out there and doing your job.”

Payton has said he’s willing to adjust his schedule and week-to-week plans to help Nix ease into what Broncos general manager George Paton called “the toughest job in professional sports.”

“It’s tough to play that position,” Payton said. “I’ve said this before, it’s definitely tough when you’re struggling on defense or you’re struggling running the ball. … You get a young player like Bo Nix, he’s got certain skills — strengths and weaknesses. Hopefully we build on the strengths and minimize the things that a young player might have to deal with to open the early part of the season.”

Nix said he will have a large group of family and friends around him, including an uncle (Rusty Nix, the brother of his father, former Auburn quarterback Patrick Nix) who hasn’t missed a season opener since Bo Nix started playing organized football.

“That’s the exciting part, a lot of these good friends and family members have been there from Day 1 and want to see the journey,” Nix said. “… And it’s those kinds of things that you respect, and it’s the fun part of playing, the memories and part of the journey, but you only get your first game once, you want to go out there and get the most out of it.”