Achieve all the application requirements to grad school,  and submitting them in a timely fashion, can be stressful if you're trying to get everything together at the same time. Now you most likely understand the virtues of a staggered approach, based on a clearly delineated timeline. Accomplishing the entrance exam for your grad program - GMAT, GRE, LSAT, or MCAT, as early as possible is one step you can take to spread out the application load.
GMAT
• Can be taken once per calendar month, up to five times per 12-month period.
• Scores are valid for up to five years.
• Administered by the Graduate Management Admission Council.
GRE
• Can be taken once per calendar month, up to five times per 12-month period.
• Scores are valid for five years.
• Administered by the Educational Testing Service and the GRE Board.
LSAT
• Can be taken three times in any two-year period.
• Given in February, June, September/October, and December only.
• Scores are valid for at least three years and up to five, depending on each school's requirements.
• Administered by the Law School Admission Council.
MCAT
• Can be taken twice per year (April and August).
• Can only be taken three times. Taking the MCAT more than three times requires special permission from
MCAT and the AAMC (Association of American Medical Colleges)
• Scores are valid for three years.
• Administered by the AAMC.
As it is in no way too early to take the test, the benchmarks listed above are given by the tests' respective administering organizations; you should contact the admissions offices at your prospective schools to verify their exact time requirements. No school requires test scores less than two years old, so you could take your entrance test one or more years in advance of beginning the application process. This gets not only one major requirement of your application out of the way; it also gives you a nice, wide window of time to squeeze the test into your busy schedule.
Being an undergraduate junior or senior, consider taking your exam during a natural lull in your course work; shortly after a semester has started or during the summer months, for example. But if you are a post-graduate, your test should be done when you have the fewest demands on your time, since preparation usually requires a substantial commitment. Plan to devote twenty or more hours of preparation for the GRE and GMAT, more for the LSAT, and even more for the MCAT (depending on your current mastery of material) for significant score improvement.
| 
