+1 on sleep. The sleep 2 nights before is critical since, if it's a big race for me, I can barely sleep the night before.

My own method of knowing when to climb off the bike - I'll take 2 days before off, the day prior when I get on the bike I will climb off of it as soon as my legs get a bit swollen and then start to return to normal size. It seems that I need to get that process out of my legs before I'll go well on my next ride.

If I can't ride the day before, I'll do 15-30 min in the morning before I leave for the race.