@Ankur Bawiskar 

1. when this should be shown below field?

Ans:- After manual selection done by the agent. we should showcase the display message under that field like "Updated by userName". eg:- updated by bhanu.

2. when form loads or as soon as agent type?

Ans :- Only agent manual changes we need that display message should show always on agent form.

Thanks,

Bhanu.