Hi 

GRE is a standardized test that is an admissions requirement for most Graduate Schools in the United States. Even though a definite answer to this questipon isnt possible, I can assure you that with consistent preparation and practise, it is not a difficult task.

Ideally, a preparation time of about 3-6 months is sufficient for GRE.

Prepare a weekly and daily study plan wherein you have set targets in terms of topics to be studied and questions to be practised. For verbal, do new words everyday and practise various verbal excercises as well.

This routine followed religiously is sure to get you a great score in your GRE.

All the best!