WALTHAM, Mass — Kendrick Perkins might be 26 years old, 6-foot-10 and 275 pounds, but on Tuesday afternoon, he was taking baby steps.

Perk returned to the Celtics' practice floor in Waltham on Tuesday, playing a minimal role as he briefly did non-contact drills with his teammates. He's still a long way from returning to game action, but the practice time was a solid step in the right direction for the Celtics' center.

"I just did the dummy offense with the guys," Perkins said. "Just got up and down a little bit, and it felt pretty good. Just went over the plays a little bit and got a little rhythm. It was good to be out there."

Coach Doc Rivers explained that he just has Perkins walking through the "skeleton offense" to get a feel for things while he slowly recovers from his torn ACL. He's had Perk do brief walkthroughs with the second unit before, but Tuesday was his first chance to really practice. The coach was encouraged by what he saw.

"Perk looked good for what he did," Rivers said. "He actually dunked a couple of times today, so that's good."

OK, OK. So when will Perk really be back? That's the tougher question. He says he's been discussing it with his doctor, but they've been unable to set a definite timetable.

With most NBA players, you give them a return date, and they'll try to one-up you and come back earlier. In Perk's case, his own estimate was a little conservative.

"Actually, his was earlier," Perkins said. "I thought it was like a little after the All-Star break, and he was thinking more late January, early February. So I'll just see how it goes and see how my knee responds to extra activity. We'll go from there."

The C's center says he had one MRI last week to check on how his knee was progressing, and he's likely to have another shortly after New Year's. Each MRI is a good thing, he says — with each one, he takes another step toward getting back out there. The next step is full-contact practice.

That's the physical side, anyway. There's also a mental component to making a complete recovery from this kind of injury, and that's something that Perk is still grappling with.

"It's basically just about having confidence," he said. "You kind of get scared the first couple times being back out there. But for me, not really. I felt all right. My timing was a little off, but I thought I did pretty well, at least for my first time back."

"It's tough," Rivers said of the recovery process. "I've been through it, every player has been through it. You do feel disconnected, and that's just part of the process. The other mental part when he comes back, which is how much he actually trusts his leg. If we can get anything out of Perk this year, I'll be thrilled, honestly. I know he's going to play, but it usually takes a year after the surgery to be completely confident."

At the moment, Perk isn't thinking too much about the big picture. He might wind up like Wes Welker, bouncing back and becoming his old self again; he might also end up like Kevin Garnett, who took a full two years to recover from his knee injury.

You never know. So the Celtics' big man is trying not to worry about the years ahead.

"I'm just trying not to have no setbacks," he said. "I'm not trying to move too fast — just take it slow and keep getting better each day."