"He'll get back here probably by the first of September," Maddon said.
La Stella had gone home to New Jersey rather than report to the Minor Leagues. The infielder was batting .295 when he was optioned to make room for outfielder Chris Coghlan on the 25-man roster. The Cubs placed La Stella on the temporarily inactive list.
The Cubs have maintained that La Stella needed to get at-bats in the Minor Leagues before he could rejoin the team. He was expected to be added when rosters expand next month if he wasn't needed sooner.
"The important thing for us was that the time spent was valuable to him," Cubs general manager Jed Hoyer said. "I think he's excited to get going. He's going to Tennessee and he's got to work his way back. That's an important factor as well. He knows he has to go down and perform and get back to playing."
If La Stella had been ready now, he might have been added on Wednesday when Coghlan was placed on the 15-day disabled list because of a right rib contusion.
"We know [La Stella] can hit," Hoyer said. "Hopefully, he's not too rusty. There are no promises, but we're confident he'll go down and perform well offensively."
There is no set timetable for how long La Stella will be at Tennessee, Hoyer said.
Maddon said Cubs president of baseball operations Theo Epstein and sports psychologist Ken Ravizza had been in contact with La Stella.
"It's a good sign, it's a good thing, we want him back," Maddon said. "I know he'll be helpful for us down the road. I like him in the clubhouse, I like his personality. It's one of those moments where it appears we handled everything well."
La Stella has stayed in touch with some of the Cubs' players through the process.
"He's so good to have off the bench, and he's so good to have in that spot start when the matchup works in his favor," Maddon said. "It should occur by September."
Carrie Muskat has covered the Cubs since 1987, and for MLB.com since 2001. She writes a blog, Muskat Ramblings. You can follow her on Twitter @CarrieMuskat and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.