How much lag should i expect from a server 8300 miles away?

Good to see another Tasmanian on here!
It all comes down to how powerful your internet connection is (server side and client side). If you are running on a server hosting site, you should expect a little lag, if it's a home network, it would differ according to the internet connection you have. Remember, "Lag" isn't measured in miles or kilometres, it is (dare I say) measured in 'pings' this is the measure of packets dropped. The higher the ping, the more "Lag" you will have.