"Hello, Arnie ... Arnold Peasegood, he's an Obliviator — member of the Accidental Magic Reversal Squad, you know"
-- Arthur Weasley's running commentary on Ministry of Magic personnel (GF7)
He is pointed out to Harry and Hermione and greeted by Arthur Weasley at the 1994 Quidditch World Cup (GF7).
Other canon notes and references
Arnie is short for Arnold, which means "eagle power" (from arn "eagle" and wald "power") (Behind the Name).
Peasegood is an Anglo-Saxon surname and means "peascods" (pea pods). It may have originally been given to sellers or growers of peascods (Internet Surname Database).
While the date printed on DP3 is 1 June 1999, the timeframe for these events is 1992-1993.