The past is the past, and when Justin Blackmon arrived at EverBank Field Tuesday, he was ready to leave it there.

"Obviously, I'm behind," the Jaguars' rookie first-round selection said following his first practice after signing a four-year contract.

"I'm ready to catch up."

Just how fast will that happen?  As Head Coach Mike Mularkey sees it, that depends on Blackmon.

Mularkey, in his first season as the Jaguars' head coach, said Tuesday while he was concerned about the No. 5 overall selection early in organized team activities this past offseason, he said Blackmon's approach changed dramatically following his arrest for DUI in early June.

Blackmon, a wide receiver from Oklahoma State, appeared to work harder and spend more time studying the playbook following the DUI arrest, Mularkey said, and the head coach said that gave him confidence in Blackmon as the offseason ended.

"I felt better when he left," Mularkey said.

Blackmon ended a 10-day holdout to open 2012 Training Camp by signing what has been reported as a four-year, $18.5 million deal. Early Tuesday, Mularkey spoke to Blackmon.

His message was simple.

"I had a talk with him this morning when he first came in, that I will know what you know based on how fast you do things," Mularkey said. "It will be evident if he's going to struggle or not, to see how fast he's working."

Blackmon upon reporting Tuesday said although he is behind, he spent the past two weeks working out in Dallas and his hometown of Norman, Okla. He said he practiced the Jaguars' route tree during that time, and that he focused on getting in the best shape possible.

"It's a lot hotter in Oklahoma than it was here today, so it was real good," he said. "I was able to run the routes, practice getting in and out of my breaks."

Blackmon said he didn't know the details of the contract, and that his decision to sign came because his agent told him an acceptable deal had been reached.

"It was hard, I wanted to be here, and like I said, I'm happy to be here and ready to get going," he said.

The Jaguars are ready for that, too, and Mularkey said wide receivers coach Jerry Sullivan has been given permission to spend time out of meetings working with Blackmon.

"He's been wanting to coach him and get him going," Mularkey said. "We all have. Jerry's going to be with him and basically be his shadow until he gets it. I don't know how long that's going to be. Hopefully, the sooner the better for all of us."

Blackmon for the past two seasons was one of the most productive players in college football, catching 233 passes for 3,304 yards and 38 touchdowns in that span. He worked only in shorts and a helmet Tuesday, but early in drills, showed an ability to get in and out of breaks and catch the ball cleanly.

Jaguars teammates said he showed that same natural ability during the off-season, but players and Mularkey alike said there's far more to being a productive NFL player.

"I think he will figure that out on his own," Mularkey said, adding Blackmon will know quickly he can't get by on natural talent. "Once you go against our corners and corners in the league you'll find out real fast that that's not how it works.

"He'll have to study, work at it, understand the guy across from him, know what the guy eats for breakfast in the morning across from him, everything to make it easier. Know the answer before the question.  That's what he's got to learn how to do."

Blackmon, the last first-round selection in the 2012 draft to sign, will be limited in practice this week by NFL rules. He passed his physical Monday, which Mularkey said meant he could work in a helmet Tuesday. He won't play in the preseason opener against the Giants Friday, and will begin full-padded practice Sunday.

Mularkey said had the Jaguars planned a padded practice Thursday, Blackmon could have participated fully that day. The team will work in shorts with the preseason opener the following night.

Mularkey said because Blackmon has yet to work full, it was difficult to evaluate just where Blackmon is physically and in terms of knowledge of the offense.

"You can't bump and run when you have no pads on," Mularkey said. "It's hard for me right now to know exactly what he has. We weren't going to put him right in and have every rep. We'll be smart with him. I just need some time to get him with the team and really see what he knows."

"That's a position that you really have to know a lot before it happens and react fast and execute the play. The guys that can do that consistently are the guys that know the offense better than the other ones."

Mularkey said although Blackmon participated in OTAs and minicamp, "he's got some learning to do," and that Blackmon over the next week or so will be "bombarded" with the same offensive installation the rest of the offensive player underwent the past two weeks.

Offensive coordinator Bob Bratkowski estimated Monday the team has installed about 90 percent of the offense.

"I'm hoping he's kept his book," Mularkey said. "He had a lot of information when he left out of here."

Mularkey said while Blackmon's talent was evident in OTAs, his progress early during that period was a concern. He said he while he didn't believe Blackmon was working hard enough or "getting it" before the DUI arrest, "I do have confidence because of what he did after his incident."

 "When he left here I was confident," he said. "Again, that's something I have to see as we go along. We still have time."

Mularkey said while he is confident that Blackmon can make up whatever he may have missed in the last two weeks, realistically, only time – and Blackmon – can decide that.

"We will know by how fast his progress happens in this camp," Mularkey said. "I believe even since the incident his approach to everything he's doing on the field and in the meetings was different after the incident. That was a good thing.

"I literally have seen him for four hours now. I can't make a judgment on him until he's been around here a while."