When did speakers first draw in the air with their fingers to indicate that a word or phrase should be heard as if between quotation marks?
I found two memorates from the 1960s describing the gesturing with fingers from each hand to draw quotation marks around a spoken word or phrase. These are recorded as witnessed in 1964-68 and 1968-69, by a then undergraduate and school student respectively. I myself recall the gesture from 1980-81.
The practice became widespread at the end of the 1980s, at least partly because of the gesture's frequent use by Steve Martin on the United States TV show Saturday Night Live.
The earliest reference I could find to the term "air quotes" was in March 1989 by Kurt Andersen and Paul Rudnick in their article "The Irony Epidemic" in Spy magazine. (Some online sources cite a 1987 source for a use by Frazier Moore, but this does not stand up.)
There is a much earlier reference to a similar but not identical gesture in the July 1927 edition of Science, which describes a woman who raised her hands above her head with the first and second fingers pointing upwards, representing quotation marks, when she wished to convey that her sayings were not original.