This winter I'd follow ZeCanon's advice and ride quite a bit of volume (8 hours a week is PLENTY for starters through Cat 3 in my opinion), with maybe 1 day for threshold work, the rest just endurance riding and some easy tempo stuff. You can add in the speed work and more intense threshold work 8 weeks away from your race day and that'll be plenty of time to get fast.
You will meet guys that are doing 12-15 (or more) hours a week, and are still Cat 4 pack fodder. They are riding above their ability to recover, and will never get faster because they aren't allowing their body to heal and progress. The key is to get as much gain as possible out of minimum amount of riding, THEN slightly increase when you start showing up to every ride extremely fresh. If you are carrying residual soreness into any of your rides at 7-8 hours a week, DO NOT increase your volume. Give it some time, and when you are ready to move up, you will feel it. I started around 6 hours a week last year, progressed to 7-8 hours a week (which took me to the top of Cat 3, enough to earn points towards my Cat 2), and a year later I'm finally able to handle 10-12 hours a week (will be racing Cat 2's this season). My cousin (former top level Cat 1) averaged 12-14 when he was winning local Cat 1 races and competed well at even NRC events. WaterRockets can crush the cat 3's on 7-8 hours of riding a week as well. A friend was on the olympic development squad riding less than 20hr a week... OLYMPIC level.