Queer studies originated as the academic term in the 1990s (coined by a lesbian), as did 'we're here, we're queer, get used to it'. It was not exclusively a slur pre-2000s - it was reclaimed long before the latest generation of LGBTQ. Some of the earliest evidence we have of it being a preferred personal term is from the 1930s, and as a community term from the 1980s. That's ~40 years.