OG 11& 12

It depends on how much time you have, and where your weaknesses lie. I wouldn't do both OG 11 and OG 12. Stick to OG 12, and then either Verbal or Quant depending on what you need the most help with. Your time could probably be better used focusing on the GMAT Prep, working through your Error Log, and honing in on your 2-3 weakest content areas in the last 3 weeks.

Review the mock tests, error log, flash cards for the whole two weeks. Find out the mistakes you did on your mock which you could have avoided . Work on them. Any small topic which you can improve on which you know the basics yet you do mistakes while solving. Timing strategy and within the two weeks you should know whether you can answer a question or not once you had thoroughly understood the question. Review everything you know till you reach that point. Don't take any mock tests close to the D Day. Finish your mocks a week or 4/5 days ahead. Search for GMATPrep Quant/SC documents and try to have a look at them. You will get adapted to GMAT Type questions. Hope this helps.