In fact we also have an idea of the rate of growth. Approximately 4 months prior, @bnewbold.net posted an article detailing how to run a Bluesky relay: https://whtwnd.com/bnewbold.net/entries/Notes%20on%20Running%20a%20Full-Network%20atproto%20Relay%20(July%202024)
This is great. We need more people trying to do so to get a sense of how decentralized things can be.