PITTSBURGH — T.J. Watt is a quick study. Growing up in a household with two older brothers, he didn’t really have a choice. Adapt or get left behind. Quickly.

Those childhood habits die hard for the Pittsburgh Steelers rookie linebacker. His mother Connie taught her boys about organization. Older brother Derek espoused the virtue of cramming spiral notebooks with information during their days together at Wisconsin, a habit T.J. embraced, one that helped fuel the transition from reserve college tight end to NFL starter on the other side of the ball in a span of three years.

“(Derek) said `I write everything down,”’ T.J. Watt said. “Coaches were always like, `Man, your brother is taking a bunch of notes.’ So I take notes every day.”

That’s not the only writing Watt does. Before he began his first season with the Steelers, he jotted down a list of goals. Some of them were small. One of them was not: be out there with the ones when Pittsburgh opened the season on Sept. 10 in Cleveland.

Done.

When Watt’s No. 90 runs out of the tunnel on Sunday against the Browns, he’ll be the first rookie outside linebacker to start in an opener for the Steelers since Aaron Jones in 1988. Five-time Pro Bowl teammate James Harrison didn’t do it. Neither did Joey Porter, now Watt’s position coach. Lamar Woodley and Jason Gildon, too.

Watt had the job from the moment Pittsburgh grabbed him with the 30th overall pick in the draft. “Day zero” as coach Mike Tomlin called it. Yet Tomlin never passed that information along to Watt, who probably would have ignored it anyway.

“I just came out here every day, working my butt off,” Watt said. “Just doing whatever they ask me to do.”

One thing they’re not asking Watt to do? Become a smaller version of oldest brother J.J. J.J., the three-time NFL Defensive Player of the Year for the Houston Texans, is a 6-foot-5 livewire who’s nearly as quick with his mouth as he is with his feet, and is in the middle of a career that could be on its way to the Hall of Fame.

T.J. is ... not that. Oh, he’s fast enough. You don’t collect sacks on consecutive snaps of your first professional game if you’re slow. Yet that’s where the similarities end. The youngest of the three Watt brothers in the NFL (Derek plays fullback for the Chargers) is also the quietest.