Hi sushi86,
Yes, historically many people improve from 600 to 700 with reasonable effort. Just take a look at our homepage to see how others have progressed.
Generally a 1-1.5 month allocation with solid study time will work. 2-3 hours on weekdays and super intense weekend sessions of 8-10 hrs is what we recommend.
You can also take a practice test online here:
www.gmatpill.com/gmat-practice-test/practice-test We would recommend focused studying on one particular subsection before moving onto the next. This maximizes your focus and retention of the material because you don't get distracted with all the different areas of the test.