1
general::
Phrase(s): start in on someone or something
to begin dealing with, discussing, or chastising someone or something. • Please don’t start in on me again! You said enough the previous three times. • When will you be ready to start in on painting the house?
McGrawhill's American Idioms And Phrasal Verbs
2
general::
1. Begin doing something, as in We started right in on the repairs. Also see START IN. 2. Attack, especially verbally, as in Nancy keeps starting in on Carl, complaining about the errors in his work. [Early 1900s]
American Heritage Idioms