That’s when the mammoth contract of Kevin Garnett comes off the Celtics’ books, a cap relief of more than $21 million, leaving the deals of Paul Pierce, Rajon Rondo, and Avery Bradley as the only ones remaining on the payroll.

Then it will be time to rebuild. But for now, the Celtics might as well have “2012’’ plastered over the locker room door — like the “Play like a Champion Today’’ sign the Notre Dame football team has. Each player should reach up and slap it for motivation, because that’s when the era of the Big Three likely will end.

And nobody in the organization denies it. Ainge’s maneuvering will give the Celtics nearly $30 million in salary cap space in the summer of 2012, when the new collective bargaining agreement will be ratified and owners are expected to have more control over guaranteed contracts and revenue sharing.

But enough of the futuristic talk. The time is now, and Ainge has no problem relaying that message to his team.

“Well, we’ll enjoy the two seasons while we have them,’’ Ainge said. “We’ll take it one season at a time. But right now, we’re doing all we can to win a championship right now. Our focus is just this year and we’ll worry about the following year next summer.

“I don’t think it’s added pressure. I think those guys know where they are in their careers. They know their window is short. They all know what opportunity lies ahead and there’s not a lot left for them.’’

There are no delusions, especially for coach Doc Rivers, who turned down a lucrative contract extension and said he would honor only the one year remaining on his deal, then consider his status next summer.

The Celtics came within six minutes of winning their 18th NBA title last June but fell apart in the fourth quarter of Game 7 in the Finals against the Lakers and are likely farther away from the crown with the improvement of the Lakers and the acquisitions of the Heat.

So training camp, which begins Tuesday in Newport, R.I., will be serious from the first whistle. Unlike last season, when Garnett was trying to get healthy and the only major addition was Rasheed Wallace, the Celtics begin camp with several new players fighting for minutes and respect.

Asked if there was a sense of urgency, Rivers said, “I don’t know if we have that yet, but we have to have that. We have to be realistic. It’s not like we have a four- or five-year window we can play with and decide to get to it.

“So I think our entire team should think each year, last year and this year again, that this should be your last shot.’’

Rivers plans to meet with the team and emphasize the importance of now.

“I think they can do the math,’’ he said. “We have to understand that each year is your last one.’’

Shaquille O’Neal, who accepted a minimum salary, said he has “735 days’’ left in his career because the Celtics offered him a second year.

“There is a sense of urgency for me, and I’m sure there’s a sense of urgency for all the other guys,’’ he said. “You only get one shot. You have to put it all on the line, and we all are going to put all our egos on the side, and we’ll see what happens.

“I have a two-year window, but anything can change. Because I know at 40, 41, I won’t have the same opportunities as I have now, which will be fine.’’

Ruland believes he was unfairly removed because of philosophical differences with the Iona administration and was prevented from interviewing for a Big East job during his tenure. Ruland coached in the NBDL with the Albuquerque Thunderbirds for a year, then was hired by former teammate Maurice Cheeks for one season in Philadelphia as an assistant but was not retained by new coach Eddie Jordan.

Looking for a college job, Ruland was approached by UDC athletic director Patricia Thomas about resurrecting the moribund program, which does not have a conference affiliation. Thomas wants the program to pursue Division 1 status and wants Ruland in charge. The Firebirds were 1-20 last season and reduced to five players for a few games because of injuries and ineligibility. But Ruland has nine returning players and some promising recruits.

“I love to teach,’’ he said. “I love to make a difference. My job is to finish them off. I have three daughters of my own and I think I am doing it for all the right reasons, but it’s definitely been frustrating.

“I haven’t had things handed to me, I earned them. To be stymied, it hurts. I am trying to turn this place around and do the right thing.’’

Ruland told New York radio host Mike Francesa in March that he believes some members of the Iona administration turned against him because he dated a Jamaican-American woman. Ruland did not want to discuss the specifics of his Iona departure, but his fall has been difficult. He pursued several lower-level Division 1 jobs but was not granted an interview.

“It’s a shame you have to talk about the color of someone’s skin,’’ he said. “And that’s still some people’s position in America and that’s sad.

“I’ve been told I have to win again, basically. I’m trying to do that, even though my record speaks for itself. All I have done since I left [Iona] is stay in basketball. Some of [the job openings], to be very frank with you, I was overqualified for.’’

Ruland is determined to bring UDC to respectability.

“I am at UDC, and that’s all I know,’’ he said. “I am content where I am at. I want to be able to pursue those jobs if that’s what I want. Trying to put this behind me and move forward.’’

“It was a marathon,’’ said Jackson. “It was long, the flights back and forth cross-country. And playing games immediately after those long flights was physically exhausting.

“I think that, by the way, helped us win that sixth game by the large sum of points. The NBA would really step forward if they took another day between those long flights.

“I kept telling Kobe [Bryant], keep passing the ball for most of the game. But it still didn’t change. He was taking those shots. But he got it together in the fourth quarter. We had a good fourth quarter. It was nice to see.’’

Jackson, who had his share of run-ins with Shaquille O’Neal, could have taken a shot at the aging center accepting a two-year minimum offer from the Celtics, but didn’t.

“With [Kendrick] Perkins out until perhaps December or January, they really bolstered themselves at the power position,’’ he said. “The Celtics, Orlando, Miami, Atlanta, they are going to have a race out there. Boston helped themselves in the process.

“Basketball is won with defense. The Celtics play defense and they know how to do it. Whether they can sustain it for 82 games in the regular season, I don’t know.’’

A sticking point was Nelson’s $6 million salary for the final year of his contract, hence the naming of Smart instead of a national search for a more expensive replacement. But it was definitely time for the Warriors to move on. After a splendid first season in Nelson’s return to Golden State, the franchise has been mired in a tailspin, primarily because of his decisions regarding young players.

What happened to Brandan Wright and Anthony Randolph? Both were considered impact players in the draft and both disappeared, their confidence shaken by the impatient Nelson.

The Warriors, partly because of a rash of injuries, were 55-109 in Nelson’s final two years, and it was time for a change. The franchise hopes to emerge as a contender once the current Western Conference powers get old.

The Warriors nabbed Stephen Curry, traded for David Lee, dumped the contract of Corey Maggette, and drafted Ekpe Udoh to join Monta Ellis and Andris Biedrins, giving them a solid nucleus. They need a younger leader, and Smart will get his chance, but he’ll likely have only one season to get it going in the right direction.

Gary Washburn can be reached at gwashburn@globe.com. Material from interviews, wire services, other beat writers, and league and team sources was used in this report.