"Barring any setbacks, I think (Rondo is) planning on playing tomorrow," Ainge said at the team's practice facility.
"I'm not sure. He hasn't played for a year," Ainge said. "What I've seen throughout my professional basketball career is that the ACL injury is something that every player has to overcome and coming back mentally, not just physically. I anticipate some adjustments and just getting used to playing and feeling confident and returning to the player that he was.
"And I think he will get there, and I don't know how long it will take, if that means a week or a month or what. He has to get back out on the court and he has to try it, and now is as good a time as any."
Rondo hinted at Friday's return earlier this week on Twitter by offering the time (in seconds) between his surgery and Friday's tipoff.
Both Ainge and coach Brad Stevens said Rodo will have a minutes restriction.
"I'm going to talk to him after practice, and the plan of attack will be he will play 18 to 20 minutes, and that would be a max," Stevens said. "So then you decide how you want to disperse those and how you want to attack each portion of the game and all those things. So that's what we're going to talk about. Obviously, he is our starting point guard, so I want to make sure we figure out the right minutes for him so he doesn't get too stiff on the bench and all that other stuff.
"Knowing Rondo, he's going to be complaining about (a minutes restriction), probably checking himself back into the game, occasionally, because that's who he is. But that's the game plan."