1) 1 month of ~2-hour rides 5-6 days a week
2) 1 easy week
3)Three weeks of Mon/Wed/Thurs/Sat 2+hour rides, Tues/Fri medium-intensity rides with Tabata intervals
4)1 easy week
5)Three weeks of Mon/Wed/Thurs 2+hour rides (hopefully a few 3+hour rides), Tabata Tuesdays (fav day of the week), active recovery Friday, FAST group ride Saturday with you attacking and sustaining 5-10 minute hard efforts.
6)1 easy week
Repeat steps 3-6 if you're only planning on crit racing. Road racing would require longer intervals (hard climbs) mixed in on your long rides.
That'll set you up to come into the spring racing season with a strong engine. Pending tactical errors and race schedule, if a cat-4 rider followed this plan, they'd make cat-3 in a month or less. Tabatas are you best friend if you want to own the crit scene. Just don't overdo them.