Right, there were several cypherpunks on the mailing lists.

And don't underestimate cryptographers from academic circles in the early days - Satoshi themselves were from a university context which you can see through the double spaces in the Whitepaper.

Also there was the larger underground cyber scene from the very beginning. Not unlikely that one of them tried it out

tomlaies

I don't think there is any way to figure that out from the blockchain data itself, and I have no idea if someone kept a log of connected peers or something like that, but I guess it could've been well possible.

Ask Satoshi, he probably did it.  LOL

Do you know if there's a way to determine how many computers were mining back then based on hash rate or by other means?

siggy47

bitcoin

Mysterious Bitcoin miner shows off oldest signature dated Jan. 2009

Satoshi's paper had been published earlier and some people could've been lurking around the forum without participating, so I think that address could be owned someone totally unknown.