sorry, posted twice by mistake

OK, I'm sure this question has been beaten to death, but when is someone ready to try a cat5 race? I would like to race this summer and I would like to begin my preparation now. I know speed's change during a race, but what kind of flat speeds should I be able to ride at solo? How many miles should I be comfortable riding per week? Can I be successful if I only ride by myself and learn how to pack ride at the race?

I know these are very open ended questions, but I feel like I need something to shot for. Basically, for those of you who race, how did you know you were ready?

Thanks.