Here is a rough study plan to get you started based both on what others have done and my own experience:
Take a REAL, FULL (including Analysis of and Argument and IR) GMAT practice test first to see where you need to really improve.
First buy Princeton Review and look over what the book has to offer. Yes the book mostly has basic concepts but there are some cool little tips you can pick up regarding the layout and thinking behind the GMAT that may come in quite handy when taking and prepping for the test.
IMO Kaplan is bleh except for their recommendations regarding test day advice/prep leading up to test day and lifestyle changes to help get ready for the test.
Go through the entire set of
MGMAT books, including Advanced Quant, methodically making sure you absorb all they tell you. Best set of study books (concept-wise) you can have.
After you've read Princeton Review and all of
MGMAT, do FULL practice tests (most people use weekends) and really analyze every single question you get wrong. There is always something to learn from a wrongly answered question. Do some (not hours worth unless you think it will really help you) practice problems from OG on days you don't do practice tests and review any questions you get wrong there as well.
Keep this habit up until the weekend before you take the GMAT. Take GMAT Prep test and analyze questions again. Then spend the week before the test doing only a few practice problems a day to keep you in the question-answering habit. Forget reviewing these, review the questions you got wrong in previous weeks. You are in review mode now just keeping the mind warm. Do A FEW practice problems using the GMAT Prep software the day before but don't review them at all or see if you got them right or wrong. It's just to keep the mind warm. Lightly review the day before the test as well.
Test day: dominate. Trust your studying and the concepts you've learned. They are identical to what the GMAT tests.
Hopefully this gives you a starting point.