Hello! You took our course, right? If so, you should still have access to the syllabus that you used during the course, so I would use that as your "scaffold"—but you're going to adjust the plan based on your specific strengths and weaknesses.
Our syllabus covers all of the major content areas / question types in our guides and in the OG, so if you use that as your base, you will touch everything.
I would start at the Foundations level. If you've been scoring in the 640 to 680 range, your foundation is already pretty solid, but you just want to make sure that there isn't anything that will prevent you from lifting further. (Also: you don't mention your Q and V breakdown, but it's possible that you'll need to do this only for one section, not both.)
What you're going to do is basically go try some (say, 3 to 8) of the problems in each chapter / at the end of the chapter first—before reading anything in that chapter. If you're getting everything right, pretty fast, it all feels good...great! Move on to the next chapter. If you're missing things or making careless mistakes, or it feels slow or clunky, then you know you need to review that chapter (or part of it—whatever part corresponds to what didn't go well).
Then you can move to our syllabus and start to follow that (depending on when you took our program, that syllabus might be a PDF document that you downloaded or it might be Atlas, our online learning management system, which launched last summer). Note that one of the first things you do in our syllabus is take a practice test. This is to give you data so that you can customize / prioritize your studies appropriately. If you've already taken a practice test in the last 4-6 weeks, just use that. If not, take another now. Use this to analyze it:
https://www.beatthegmat.com/mba/2018/05 ... ats-part-1This analysis is going to take you a couple of hours at least—but once you're done, you'll know what to prioritize and what NOT to prioritize. Then start working through the syllabus, but increase or decrease the amount of time and effort you put into various tasks based upon the priorities that came out of your practice test analysis. (And you can adjust your priorities as you continue through your studies and gain more data.)
Each time you take another practice test (follow the syllabus—3 are assigned in total), do the analysis and then adjust your priorities accordingly as you continue through the syllabus. (Don't wait until you do everything and only then take another CAT. You need the data as you go to help you prioritize appropriately.)
Note: the syllabus is designed to run for 9 weeks and you said that you're trying to make a 40-day plan, so a big part of your prioritization will involved deciding what *not* to do. Don't just try to study for 40 hours a week and do everything—you'll burn out. (And, anyway, you don't need everything! You're already in the mid-600s, so there are plenty of things you're already good at. Don't re-do that material just because it's on the syllabus.)
Good luck!