Is it valid to fast for the expiation of breaking an oath with the intention made an hour before Fajr, and is it obligatory for it to be consecutive?

According to the majority of scholars, it is a condition to form the intention (niyyah) overnight for obligatory expiatory fasting (kaffarah), and forming the intention overnight means that it occurs between sunset and the breaking of dawn. The expiation for an oath (kaffarat al-yameen) is fasting for three days, and it is preferable to fast them consecutively to avoid scholarly disagreement. Fasting for the expiation of an oath is not sufficient unless one is unable to feed ten poor persons, or clothe them, or free a slave.