There have been times where government has use of technology because the general public so my guess would be Q has access to something that makes posting down to the exact second years later possible. The odds of posting down to the second are so low though so it must be some sort of technology that exceeds what we currently use.

If you post online from your home computer or your phone, you'll be on a website or an app and that will be connected to the internet but then the website Q posted on needs to also be perfectly reliable too. This requires multiple things to be perfect every time and that's rare.