This might be a bit off tone compared to the other stories but bare with me - I promise to be brief.
I really wish somebody had smacked me over the head a few months ago and told me to take a look at the Gmat questions, so I'd know what to expect. I'd have done it a lot sooner if I was aware of what the test was really like. The thing is that all the talk about 3 month prep schedules can really give you a strange opinion about what's coming. While I am in no way speaking out against those schedules (I have nothing but respect for the people who spent the time and effort to design them), they're not for everybody and they're not the only way to get a decent score. After all, the Gmat tests you on number of things that you've picked up during your life and without knowing it, you may have been practicing for the exam for years.
Do you still remember your high school math?
How good were you with it in the first place?
Do you enjoy reading books in english even if it's not your native language?
Does your undergraduate education offer you a chance to practice your verbal skills?
All of these and many more might just be enough to give you a pretty decent head start on the preparation.
My word of advice? Figgure out how your current capabilities match up to your needs (for instance, my school of choice only wanted 600 points) and only then decide on what needs to happen. Do this as early as possible and you might save yourself a big headache.
My score: 730
Materials used: Almost all the sample questions from
the Official Guide For The Gmat Review 12th Eddition (not much from the theory, though).
Time spent: 10 days. It occurred to me, one bright and sunny afternoon, that if I wanted two shots at the Gmat before my app. deadline was up, I'd have to take it before the 15th of May. I chose the 12th. That was on the 30th of April and I spent exactly 10 days in preparation for it.
So, yeah...think a little before you start buying the books en masse.