Not long after 4 p.m. on Sunday, Sept. 8, nothing Daniel Jones accomplished, the eyes he opened and the passes (85 percent of them) he completed during the Summer of Daniel will matter to the Giants as they take the field at AT&T Stadium to face the Cowboys in the regular-season opener for both teams.

There is a time to develop and plan for the future — and a time to get down to the serious business of knocking heads with a fierce rival.

Jones is the starting quarterback in waiting for a franchise that for the past 15 years has leaned on one player to guide their offense. When the ball is snapped and the Cowboys come steamrolling in with a defensive swarm, Jones, the rookie, will be on the sideline and Eli Manning, the veteran, will be, as usual, in the middle of the action.

You remember Mr. Manning, don’t you? Unassuming gentleman who took in stride (like he does most everything) the arrival of his replacement as he prepped for an unprecedented 16th season with the Giants. All that focus and attention heaped on Jones the past few months may gear up again at some point this fall or winter, if the Giants and/or Manning are floundering. For now, though, Jones moves into the background, and front and center, with little fanfare, is one of the most iconic figures in franchise history, although no one would know this to be true based on all the conversations and questions swirling around Jones this preseason.

“I think [Eli’s] had an outstanding offseason,’’ coach Pat Shurmur said Friday, the day after the Giants completed a 4-0 preseason. “It started by what he did by himself before the OTA offseason program started. I think he’s had, in my mind, an outstanding camp from the practice setting. He’s executed well in the time that he’s been in the game. He’s certainly a guy that’s got a lot of experience, and when I look at him, I just see a guy that’s much more comfortable in the system for the second year in a row, and I’m looking forward to him having a really good year.’’

There was a commitment made to accelerate Jones’ learning curve, and he received most of the workload in the four preseason games. As a byproduct, Manning attempted fewer passes (13) than in any of his previous 15 summers with the Giants.

During training camp, Manning put in his requisite work and his 38-year old body held up just fine. Jones is new and thus was the center of attention. Manning on a day-to-day basis existed more under-the-radar than any other summer of his career.

“I’ve definitely seen a lot of improvement with Eli,’’ said tight end Evan Engram, beginning his third season with Manning. “Each camp I’ve had with him he’s done really well and worked really hard, but for this camp it felt a little different. There’s more confidence, you could tell he’s more comfortable within the pocket and he’s been slinging the ball around all camp and hasn’t slowed down.

“I’m very excited to get on the roll with Eli, and just the things I’ve seen and the things we are talking as an offense and the things we are working toward — we’re kind of adding things to the system and putting guys in the right spots and trying our best to make him successful. I’m really excited about it. I can’t wait to get the first snap going.’’

Safety Jabrill Peppers, a 23-year-old who grew up in East Orange, N.J., spent his formative years watching Manning win two Super Bowls for the Giants. Peppers spent his first two NFL seasons with the Browns, making this his first experience with Manning as a teammate.

“Eli was everything I thought,’’ Peppers said. “A guy who has seen it all, he has played a ton of ball. A two-time MVP, champion, he has played in the tough games, he has basically done everything you want your quarterback to do.

“I definitely see the greatness that he has, whether it’s finding the open guy or putting the ball where only his guy can get it, diagnosing the coverage, checking out to get those guys a better call. I think that in this league if you have a quarterback that can do that and do it at an exceptionally high level, it gives you a lot of opportunities to win ball games.’’