LAKE FOREST, Ill. -- Chicago Bears quarterback Jay Cutler was not shy about admitting Tuesday that he might not know the breadth of the team’s new offense by the end of the season, much less the start.

“It will extend to Week 15,” Cutler said of the learning curve. “It’s going to be a process throughout the entire year of us staying on top of things and knowing exactly what (coach Marc Trestman) wants us to do out there. It’s a week-by-week thing. It’s never going to be perfect.”

Cutler isn’t just an experienced NFL quarterback, he is also a veteran of learning new offenses. And it’s quite possible that Cutler has never fully grasped the full scope of any of the offenses he has been required to learn before moving on to the next.

Despite what he doesn’t know by the season opener, though, that shouldn’t mean the Bears will be limited offensively when they take the field Sept. 8 against the Cincinnati Bengals.

“I think that we have a bulk of the offense and we’ll continue to grow because that’s what normally happens with all offenses in the National Football League,” Trestman said. “You start working in a certain direction, you pick up on variations and you start thinking about things you can do within the framework and the foundation you have.”

Since the first team won’t be playing in Thursday’s final preseason game against the Cleveland Browns, the starting offense has been breaking off from the second team at practice this week to get in their own repetitions with the Bengals in mind.

Even at this late juncture, the coaching staff is trying to find a game plan that suits the team’s skill set.

“We’re headed in the right direction I think,” Cutler said. “Coach Trestman and (offensive coordinator Aaron) Kromer, and all of the guys, have done a good job of piling a lot of stuff on us and then limiting it back and trying to figure out what we’re good at and what we can be successful at during the regular season.

“It’s been fun to see the progress the guys have made and how hard they have worked and studied throughout the offseason.”

Still undecided is the right side of the offensive line, where rookies Jordan Mills and Kyle Long continue to try and prove themselves.

“Well, we’re not ready to name starters yet,” Kromer said. “We’re still battling. Those two have done a good job of handling the pressure and by far they are not perfect but they have handled the pressure and have done a solid job in the games.”

Cutler, who has had his run-ins with his own offensive linemen in the past, is saying, for now anyway, that he is impressed with what he sees from the rookies.

“They’ve done a great job,” Cutler said. “They want to be out there. They want to be the two guys starting in Week 1. They’ve done a lot in these last two games to go ahead and hopefully solidify those spots, but we’ll see how it goes.”

Once the line is settled, it will go a long way toward determining what offensive package the Bears are able to use, although whatever is decided for the opener won’t necessarily be the plan moving forward, even if it has some success.

“I would assume that we’ll continue to evolve as we go on,” Trestman said. “That doesn’t mean we won’t be doing things well when we start. We want to do things well when we start. But that’s what most offenses do, they evolve in certain directions or there are personnel groupings that become more prominent because players start stepping up or ascending and they move people around. Those are all good things.”