Amid the pandemic turbulence, many big firms pushed back first-year associates start times—which are ordinarily in September or early October—to January.

Law firm leaders and legal industry observers said they don't expect a three-month delay to have much impact on associates' career development or law firms' workflow. But the changes for first-year associates in 2020 raise longer-term concerns about how well firms will be able to train and instill firm culture in new associates working from home and whether that could affect associate retention in the long run.

"It's hard for firms to build loyalty and instill culture if people are not face-to-face," said Joan Newman, who coaches senior associates and partners on their career development.