start in on

verb2

1. •
   (informal) To make a start on; to begin to tackle.

   • She started in on the closet, hoisting boxes from the shelf and placing them on the floor. — 2013
2. •
   (informal) To attack verbally or physically.

   • She was always worried about Laura when she was in gymnastics. When her teammate died of complications from anorexia, she really started in on her about her weight. — 2009