The fragment dates to 250 but, as Fr. Longenecker notes, "if this hymn to the Virgin dates from 250 AD we can deduce that it must be a written record of an earlier practice. Think about it, by the time something is written down for use in the liturgy it must already have been in use for some time. Furthermore, if this prayer is part of a document that is a copy of another document, then this also indicates that the actual practice is earlier than the manuscript itself."
Speculation on his part.