We used to drive down on Saturday but now we get the train, it's such a good service these days. Never had any ill effects.
Even in a good hotel, you don't sleep as well as at home do you, so I'd rather not have two restless nights before the race myself.
I keep promising myself to get a cheap ticket and go to the expo on the Wednesday though, it would be nice to lie in on Saturday and take a late train, stroll to hotel and sleep.