I believe that if someone asks you... "how often"... it implies you have done something before related to that subject once at least.
How often do you go fishing? (com que frequencia voce pesca?)
well... twice a week.
Have you ever gone finishing? (vocÍ jŠ pescou alguma vez?)
no, I haven't.
Do you ever go fishing? (JŠ te ocorreu de pescar alguma vez?)
No, I don't.
[I AM NOT A TEACHER]
Interested in Language