Only Sundays, Solemnities, and very important Feasts (if they fall on a Sunday ((such as the Triumph of the Cross)) have Evening Prayer I. “Regular” feasts, memorials, and optional memories do not utilize Evening Prayer I, just the evening prayer of the usual weekday before.
St. Thomas Aquinas never has an EP I, the night before his Memorial, though the Nativity of John the Baptist does have an EP I the night before, because of the Solemnity.