I did 100 BC Cultural Victory (Deity, X360, o777o). 1st run (after taking 3 capitals, included walk in on Athens), 4000 gold left (after rushing all wonders). This time 3 GB

(1 GB from USA) - too much, too late, useless (100 BC is easy without GB). I needed GS for Corp (not GB), so production city was ready at 700 BC (should be at 800 BC) due to lack of gold. With early GS and 1 GB 200 BC should be possible.
As for Dom: i can see 1900 BC (but i'm not sure about gold for roads), faster only with early walk out (but American walk out is ~1700 BC).
I knew it. But this week this glitch/cheat will give huge advantage (~2 turns, walk in on Kyoto).