Marvin Mims Jr. had to adjust on the fly.

Working across the field on a critical third down Sunday against Cleveland, he had a ball coming his way from Russell Wilson for an easy first down.

The ball got tipped, though, and redirected against Mims’ momentum. He reached back, snared it and made sure the Broncos kept the chains moving with a 16-yard gain en route to a second-quarter touchdown.

“It was pure reaction, just locked in on the ball,” Mims told The Post. “I haven’t got many chances lately, so I saw it coming and it kind of misdirected. …

“We really needed it, too, on a third down. So it was pretty cool.”

The trajectory of Mims’ rookie season has taken a similar mid-flight change, and he’s doing his best to make the adjustment as a critical stretch of the season arrives.

“It’s just waiting for the opportunity,” Mims said. “It’s kind of tough, especially having success early and then now it’s kind of stalled out, but you’ve got to be ready for your opportunity. Any time your number’s called, they don’t care when’s the last time you made a play. They want that play right there.

“So you just have to be ready for it.”

The Broncos traded up this spring to select Mims with the final pick of the second round (No. 63 overall). Then in Week 2, Mims logged the Broncos’ lone 100-yard receiving game of the year when he caught two passes for 113, highlighted by a 60-yard touchdown.

Since then, though, big plays have been tougher to find. His playing time stayed suppressed for the first half of the season.

In three games since the Broncos’ bye week, though, he’s been on the field a lot more. In fact, he played more snaps than Jeudy in Week 10 against Buffalo. All told, they’ve played virtually the same amount behind Courtland Sutton — 115 snaps for Mims, 129 for Jeudy.

That hasn’t translated to big production so far — four catches (six targets) for 36 yards and a carry for 11 — but like a baseball player who’s hitting the ball hard but lining into outs, the playing time could be a harbinger of a breakout on the horizon.

“Marvin’s done a great job — obviously he’s one of the top special teams guys in the league, and I think also from a receiver spot, he’s made some great plays,” Wilson said. “He’s explosive, has made some good plays for us in the last game, plays here and there. It’s just being consistent every day. We have a long list of great receivers coming in and out of the game.

“But he always practices well, he’s got great speed, great talent and he’s got great confidence.”

Denver has leaned heavily on its run game and doesn’t have a receiver averaging more than Sutton’s 51 yards per game. Houston, though, has allowed the sixth-most passing yards in the NFL. So opportunity may be afoot for Mims and the other receivers.

One other interesting wrinkle: The Texans feature one of the league’s most productive rookie receivers in third-round pick Tank Dell. Dell has 709 yards this year, second among rookie wide receivers behind the Los Angeles Rams’ Puka Nacua (924). Mims is 14th at 286 yards.

After the draft, Payton said he thought Mims and Dell were the two best return men in the class, too, and recently Payton said he was impressed with how Dell’s produced right away.

“I think it’s a position that’s hard to come into our league and play right away,” Payton said before Denver played first-round pick Jordan Addison and Minnesota. … “Some of these offenses that they’re coming from, they just lined up left outside or right outside. Now we’re saying, ‘You’re going to be here in pro, and here in slot.’

“The one thing we try to do a lot when we’re looking at receivers is gauge where they’re at mentally and what that transition is going to be like. I’ve had experience in both cases. Robert Meachem, it took him a year, but man did he come on. Michael Thomas, it was immediate. I think it can vary.”

Payton didn’t have much concern Wednesday over Jeudy missing practice because of a groin issue, and Denver should get Brandon Johnson back from injured reserve this week, so the competition for snaps may only get stiffer for Mims. Even still, he and the Broncos are all confident a breakout is coming sooner rather than later. Maybe it’ll come Sunday for Mims, a Frisco, Texas, native who said he’s got “a lot of family and friends” coming from the Dallas area and from Baton Rouge, Louisiana.

“You always want to be on the field more and get more opportunities, and I’m out there getting more of a feel for the game, putting more stuff on tape,” Mims said. “The biggest thing is just being ready for your opportunity, because you never know when it’s going to happen.”