Introduce yourself here
, then browse through here
. Currently the first page threads will full of the results, but go through the remaining pages as well and you'll get all information about when to start, how to start, which coaching class to attend, whether to attend a coaching class!
As for your current questions, you haven't written whether you work or not. Anyway, if you're aiming for CAT08, then start working on your basics - both Verbal and Quant. CAT is now evolving so rapidly that it is useless to follow any preconceived notions. Get your basic fundae right, and you'll have a better chance of giving the exam. Go through the Exam Resources section
as well, and you will find many study materials there.
In my opinion, a person with proper basics and good confidence can do without a coaching institute as well. As I said before, the purpose of a coaching institute becomes irrelevant when there is no fixed paper pattern. But its entirely your call. at the least, join a test series of any institute.
Don't give CAT07 just for trying out. Give it your best shot and who knows it may save you a year.