The Visitation was kept in the Western church for centuries on 2 July, a date without any independent claim to represent the actual timing of Mary's journey, chosen instead for reasons of the medieval liturgical calendar. In 1969, the Roman Catholic Church's calendar reform moved the feast to 31 May, positioning it to fall between the Annunciation on 25 March and the Nativity of John the Baptist on 24 June, so that the liturgical calendar would follow the narrative sequence Luke's Gospel itself describes rather than an older date detached from that sequence.
This kind of calendar adjustment illustrates a broader point about how Christian liturgical dates function: many are organized to express theological and narrative relationships between events, such as the nine month gap between Annunciation and Christmas or the six month gap between the conceptions of John and Jesus that Luke's text specifies, rather than to record independently established historical dates, which for events this early in Jesus's traditional biography are not recoverable through any surviving source.
Different Christian traditions have made different choices about exactly where to place the feast, and Eastern Orthodox churches, which did not adopt the 1969 Western reform, generally do not observe a separate Visitation feast in the same form, reflecting the broader divergence between Eastern and Western liturgical calendars that developed over many centuries of separate development.