can I quit job after I got GC? - Sure, (BUT)

U can do anything if it's employment-based LPR. Ur job only affects ur wife's 485 if u stopped having income for 2006 or the followng years before ur wife got her GC. If wife got an interview, she had to ur tax info as she was a derivative beneficiary who relied on ur I140 (assuming she's not working either, no income for the family). Only in this scenario, u might have a problem as it seems that u intend to become a full time student.