The one certain fact about Maia's Roman worship is a specific, dated, recurring act: every year on the Kalends of May, the first day of the month, the flamen Volcanalis, whose ordinary duties belonged to Vulcan, sacrificed a pregnant sow to her. A pregnant animal was a common offering to earth and fertility deities in Roman practice, read as an offering that carried the promise of increase inside it, which is part of why the rite was considered fitting for an earth goddess whatever her ultimate identity.
Whether the month of May actually takes her name is itself unsettled in the ancient sources, and Ovid's Fasti, Rome's most careful surviving account of its own religious calendar, records the disagreement rather than closing it. One explanation Ovid offers ties Maius to Maia directly, the goddess honored at its opening. A second and unrelated explanation ties the name instead to the maiores, the elders, set against the following month, Junius, read as honoring the iuniores, the young, so that the two months together would commemorate Rome's generations rather than any goddess at all. Ovid himself declines to choose between the two accounts, which is typical of how the Fasti treats contested etymology throughout the poem: it offers competing explanations of Roman practice rather than manufacturing a single tidy answer where the Romans themselves plainly had none.