waiver I601 before or after denial ?
 

Dear all,
I got a dui conviction three years ago,
and am about to apply for nonimmigrant visa
at us consulate.
Since according to form of156, i am
"ineligible" because of the conviction, will
I have to file waiver of excludability I601 ??
Before applying for visa or in case of denial ???
Will I need to write down a statement
for consular officer ??
Thanks for help.
Max