The origins of this custom are not explained in detail, but the use of the Bough of Return was particularly associated with vessels making the journey from Númenor to Middle-earth. The first such voyage was made by Vëantur in II 600, so in this sense the Bough of Return cannot predate that year. It is perfectly possible, of course, that it developed from a tradition among those making shorter journeys by sea around the coasts of Númenor during the earlier Second Age. Ultimately the Númenóreans adopted this custom from the Eldar of Eressëa, and in that sense among the Elves it might very well have predated the foundation of Númenor itself.