The best time to take the GRE is either in Semester V or VI. The earlier a student takes the GRE, the better it is as at higher grades, the study, and co-curricular work increases. Moreover, the GRE score is valid for 5 years. So, it is advised to take the GRE in either the 2nd or the 3rd year of your education in the case of 4 yrs undergraduate. The final year should be kept for application planning.