Hey,
I agree with Myessay that about 3-4 months is about right for GMAT Prep.

As for when to take the GMAT, Ideal is to have your test score by May of the year that you want to apply at the latest (in an ideal situation of course! ) Because this gives you another month and a half to retake the test should you not get the score you are seeking. Then come mid-June you are going to want to start working on the essays which will begin to be released about then. That is more or less an ideal schedule. And in the meanwhile you should at least research the universities that interest you. It's maybe a bit early to start thinking about strategy, but at least you can get know the schools and the programs and start thinking about where you want to apply, and where you might fit.


And yes, you CAN get a 730 without a course, but most people do better with one. Depends on you, how good a test taker you are, how disciplined, etc. But still a course can be very helpful.