The Yankees captain said last week in a statement that this will be his final season, and he planned to discuss his decision during a news conference at Steinbrenner Field on Wednesday, when New York's position players report for spring training.
''It's probably going to set in a little more, because I'm actually going to hear it instead of reading it, and see it come out of his mouth,'' Girardi said Tuesday.
Girardi joined the Yankees as a catcher in 1996, when Jeter won the AL Rookie of the Year award, and was his teammate for four seasons. He's entering his seventh year as Jeter's manager.
''I think about when he came up, when he was there every day in '96, how youthful he was - and God, he looked so young - but how mature he was as a player and what he blossomed into,'' Girardi said. ''You think about all the things that he's done, it's kind of what rolls through your mind. And then you kind of look at yourself and say, 'Where did all the time go?'''
Most Yankees players are expected to attend the news conference, to be held in the pavilion behind the third-base stands. It will be similar to Mariano Rivera's news conference last March 9 to announce his retirement decision.
''I'm excited to play with Derek. He's always been great to me whenever I've gotten on base,'' new Yankees center fielder Jacoby Ellsbury said. ''Just me coming up as a young kid. I always had great respect. It will be exciting to play with him his last year, but it would have been nice if I had a few more years.''
Jeter, who turns 40 in June, played just 17 games last year after breaking an ankle in the 2012 AL championship series opener. He has been working out for about a month at the Yankees' minor league complex and says he feels completely recovered.
Brendan Ryan, signed as a free agent during the offseason, figures to back up Jeter at shortstop and expects many fans won't be pleased on days he is in the starting lineup instead of the Yankees captain.
''Embrace the boos,'' Ryan said of his mindset.
NOTES: Kelly Johnson, another free-agent addition, brought three gloves to spring training: for first base, infield and outfield. Girardi said he expects Johnson to share time at third base in addition to being Mark Teixeira's backup at first. ''I think we kind of envision it as a platoon, but if he's hitting lefties, then all of a sudden it doesn't become a platoon,'' the manager said. ''We don't have a set infield necessarily like we've had in the past at a couple of positions, so I think at times you'll see us move people around and kind of see how it's going.'' ... RHP Masahiro Tanaka threw 35 pitches to catcher John Ryan Murphy in his third bullpen session. Asked what his favorite activity was at spring training since arriving last week, he said ''bullpen'' in English. Tanaka threw all six pitches. ''You need a lot of fingers,'' Girardi said, thinking about signals from the catcher. Tanaka said he's still jet-lagged and has only been to the hotel and training complexes. ... Murphy, who caught Rivera's final pitch in September, is going by ''John Ryan'' instead of ''J.R.'' He had been known by his full name until he enter pro ball. ... Seattle manager Lloyd McClendon responded to criticism of Robinson Cano by Yankees hitting coach Kevin Long, telling ESPN.com ''I'm a little surprised that Kevin Long is the spokesman for the New York Yankees. I wonder if he had any problems with Robbie when he wrote that book (''Cage Rat'') proclaiming himself as the guru of hitting.'' Long was quoted in Monday's editions of the New York Daily News as saying ''If somebody told me I was a dog, I'd have to fix that. When you choose not to, you leave yourself open to taking heat, and that's your fault. For whatever reason, Robbie chose not to.'' Yankees GM Brian Cashman said he was surprised by Long's comment. ''I know our fans have had issues,'' Cashman said. ''Robbie was an incredible Yankee. I never had an issue with Robby. He played every day. He played practically every inning and he performed.''