Is it possible to send a thank you note too early?

I just finished a phone interview about 30 minutes ago and got straight to writing the thank you email. I've finished it already, but now I am worried that it is too early to send it? Is that a real problem or am I just overthinking? I would ideally wait like an hour or two but its almost 5pm in my time zone and I don't know if I should wait until tomorrow or do it yet today. Any insight would be helpful!