Translation:I have not eaten chicken since Saturday.
It would be unusual – it would mean that you gave up eating chicken on Saturday and don't intend to eat it again – but grammatically correct. How would you say this in Portuguese?
It's good to know about that usage of the present tense. In duolingo this is the first introduction to it I think?
We normally wouldn't use days of the week to explain that, but I think the closest translation would be "Eu não como mais frango desde sábado" (I don't eat chicken anymore since Saturday). Sounds kinda strange because it's too short, people usually count the days, weeks, or months in that case, e.g. "Faz três meses que eu não como mais frango" (It's been three months since I've stopped eating chicken).