start on somebody/something phrasal verb ( see also ↑ start )
1 . to begin doing something or using something:
You’d better start on your homework.
2 . start somebody on something to make someone start doing something regularly, especially because it will be good for them:
Try starting your baby on solid foods at four months old.
3 . British English informal to begin criticizing someone or complaining to them about something
start on somebody/something at
Ray’s wife started on at him about spending too much time in the pub.