I haven’t had access to any of my pre-digital photos, so at present the earliest one I have is this Northern California Black Walnut from November 2002
https://www.inaturalist.org/observations/73465704
I’d just gotten by first digital camera (a Canon ELPH - super small and really durable) and was testing it out.
If I ever get back to my old prints and negatives (all in storage in a different country right now), I’d have some observations from the early 90s as my earliest ones… maybe from the 70s and 80s if I used photos that I didn’t take but that I’m in from family photos.