Typical first-day change in specific gravity

I recently started my first BIAB all-grain brew, but unfortunately my hydrometer broke before I could get an OG reading. I was targeting around a 1.065. Just around 24 hours later I took a reading and got a 1.030.

I also accidentally overpitched the yeast somewhat significantly (~1/3 packet of Safale US-05 for a 1 gallon brew).

I understand there's really no way to know for sure what the OG was, but I'm interested in knowing by roughly how much I undershot the mark.