It is going to work, Woody Johnson insists. When? Who knows? That’s the message the Jets owner offered his paying customers yesterday during an offseason in which his team underwent tremendous change and has the look of a rebuilding franchise. “Everybody is on the same page,’’ Johnson told reporters at the NFL career development symposium in Philadelphia. “We’re trying to make the team better each and every day. We’ve made some dramatic changes and it’s going to take a little bit of time for these changes to take hold, [but] I think they will take hold. I’m not going to predict exactly when, but they will take hold.’’ Fans, of course, want to know “when,’’ but Johnson did not make any promises. Following a 6-10 season, he fired general manager Mike Tannenbaum, hired John Idzik and refused to fork over huge bucks to extend the contract of cornerback Darrelle Revis, whom Idzik traded to the Buccaneers. The whirlwind roster purge also relieved the Jets of starters such as tight end Dustin Keller, defensive end Mike DeVito, safety LaRon Landry, linebacker Bart Scott and defensive lineman Sione Po’uha, all of whom were either not re-signed in free agency or released. Finally, the Jets also parted ways with Tim Tebow, but not before signing veteran David Garrard and using their second-round pick on Geno Smith to challenge Mark Sanchez’s tenuous hold on the starting quarterback job,