If your score is currently in the 600 to 650 range, than you have about 70 to 120 points to go to hit your goal. That's unlikely in one month - most people would need more time.
What is more important to you: taking the test in one month or hitting 720? You don't have to make any decisions right now, but you should think about what you want to do if you aren't in your goal score range in a month. Would you rather take the test anyway but lower your goal score? Or would you rather postpone the test?
How have you been studying for SC and CR so far? What materials have you been using to learn how to do these types of questions? (Note: I'm talking about materials that teach you strategies for both and grammar for SC - not just practice problems.)
Here are some SC resources:
http://tinyurl.com/scprocesshttps://www.manhattangmat.com/blog/inde ... st-glance/From there, if you haven't already been using our SC Strategy Guide, I would learn everything in the main chapters.
Then, if you get yourself to the point that you can handle more advanced questions, use this:
http://www.manhattangmat.com/blog/index ... orrection/For CR, start here:
https://www.manhattangmat.com/blog/inde ... reasoning/and use our CR Strategy Guide if you want more depth and practice.
For the timing stress issues, try these:
https://www.manhattangmat.com/blog/inde ... mat-score/http://www.manhattangmat.com/blog/index ... anagement/Also, how is your time management overall? If you don't know what your timing problems are (or think that you don't have any - EVERYone has some timing issues), use this to analyze your tests:
https://www.manhattangmat.com/blog/inde ... ts-part-1/and use this to help with whatever your timing issues are:
http://www.manhattangmat.com/blog/index ... nt-part-1/