1) Are you riding with a team or solo; and
2) What kind of events are you contesting?
I do most of my planning 3-1 days prior to the event . You'll want an easy day or two to recover from training, so that's the most important part of your initial planning- that, and scouting the course. There's no point in over-planning since the race itself is so fluid. Look at Gilbert; a year ago, everyone knew his tactic would be to sit-in and just attack on the Cauberg, and that's a pro-level plan. Eat right, know the course, stay near the front, try to be first.
If solo, I would say recon the course, check weather the night before, try to figure out where the obvious challenges are on the course, and have all of your gear/papers/bike packed, prepped, and tuned the night before, and be well-versed in the particular course rules and stewards' plans. Day-prior nutrition should be common-sense; starches, limited fiber, avoid heavy grease, favor foods with polyunsaturated fats.
In terms of strategy, it should go without saying that you should follow a tapered program in the days before your event. There's no point in taking the start sore or exhausted when you can easily avoid it.
If you have a team, focus on the basics; what are your team mates' strengths, who has the best fitness at the moment, are you going to protect a rider or just try to stay together.
Road race or crit? The road race would require more recon and planning/strategy. In the crit, stay on the front, period. The crit also rewards day-prior recon of the course. If you're going to dodge the same manhole covers and frost heaves 20-60 times, you should be very familiar with their locations. Also, since crits favor momentum, try to find the best (safe) lines through the turns. Since any car can dump it's entire oil pan on a city road at any time, getting a look at the road surface the day prior and morning of your crit is big.