Hi there!

That's great that you have a little more than 4 months to study! I'd suggest starting with a 3-month plan, and then re-evaluate at the end of 3 months. Glad to see you using Grockit as well!

These books are awesome -- you may want to pick up Powerscore CR or Veritas RC if you need extra Verbal practice, depending on how things go.

These are the main 4 tips I think people overlook:

Create an Error Log. Re-take quizzes and practice tests from the very beginning of your GMAT studies. Do you find yourself getting the same questions incorrect? This can be a sign that you haven't learned the content you think you have. Be honest with yourself about what is "sinking in" and what is not. Use an Error Log to assess. You can find many templates online including on BTG!

Review all questions. Use the 40/60 rule. 40% of your time should be spent actually answering questions. At minimum, 60% of your time should be spent reviewing.

Take at least 1 GMAT practice test per week. Don't take your practice tests sitting cross-legged on you bed. Utilize your desk and scratch pad as you would on the actual test. Your body needs to adjust to what it feels like to take a 3+ hour test. Because you only have one month to prepare, you should plan to take 4 practice tests, although 6 would be ideal.

Use a strategy for each question type. Not only do you have to choose a strategy that works for you, but you have to implement it every time, practicing enough so that is becomes second-hand. Ballet dancers practice a pirouette millions of times, so that when they perform onstage they don't have to think about it. You want to do the same thing for GMAT.

Good luck!