My oldest research grade one is this Common Eider I drew in my teenage notebook on 4 September 1976: https://inaturalist.ala.org.au/observations/1818918 - I think the agreement was generous.
I have uploaded media-less observations back to 26 August 1976, which is when I first started keeping a notebook.
My earliest directly uploaded observations were in 2008, but (being in Australia) I had to wait until the next day to avoid the site telling me I couldn’t add records in the future - that was quickly fixed.