Actually 5 Gold setup + 3 Gold plot = 8 GOld...add in one Seat of Power and one Narrow Seat and you are there for a total of 13 gold worth of characters. And I didn't mention every character/card that helps for a first turn win.
But no, you won't be regularly pulling off the first turn win in a tournament, but the odds have increased greatly. As well, even if you are only getting 8-10 power the first turn, it makes it that much easier to close it out on the second turn.