The appropriate time to begin working on having an impressive grade point average is on the first day that you are in a course that awards a grade and college credit (this may be while you are in high school). Actually you should begin even earlier to make sure that you are in the most appropriate course.
Santa Clara University Pre-Law Manual informs us that, "While the maximum GPA of 4.0 ('straight A's') cannot be a realistic expectation for more than a few highly gifted and highly motivated students, it should be the goal of every pre-law student at the time he or she begins college work, and every effort should be made to come as close as possible to that goal. Since law school is a rigorous academic program, admissions officials want proof (i.e., a high GPA, particularly in your last two years) that you can succeed ... . A GPA below 3.0 will harm your chances of gaining admission to law school and may need to be explained.explained."
HOW LAW SCHOOLS ADMISSION COMMITTEES
MAY LOOK AT THE UGPA
The University of California at Berkeley Career Center indicates that, "Admissions committees not only look at your cumulative GPA from all undergraduate colleges and universities you attended, but also consider a year-to-year GPA breakdown. All courses taken for a letter grade are considered in this breakdown; in other words, the GPA in the major is not typically considered as a separate element. Because law schools examine your GPA year-to-year, substantial and continuing academic improvement will work to your advantage; improvement in grades reflects not only your ability to work hard, but also your ability to maneuver through college while grasping more difficult material."
The Florida State University Pre-Law Handbook advises that, "Many law schools consider performance trends along with your numerical grade point average. Thus, schools may discount a slow start in your college career if you perform exceptionally well in the later school years. At the same time, admissions committees may see a strong start followed by a mediocre finish as an indication of less potential to do well in law school.