Hii

GRE exam is the standardised test accepted by the business schools across the globe for admission to management courses.
There is no specific date for this exam. The candidates can appear in the exam 5 times in a period of 12 months. This has a condition that the two consecutive exams must have a gap of 21 days in between. 
To know more about GRE, you can go to the following link
https://studyabroad.careers360.com/articles/gre

Hope this helps
Thanks!!

Hello,dear 

Well ,you can appear as much times as you want there is no limit in gre exam, but the thing happen is that if you attempt many times it would be counted and some graduate schools may average  your scores ,and as well money waste.

Hope this will help you!!

Hello dear

You can take the GRE revised General Test once every 21 days, up to 5 times within any continuous rolling 12-month period (365 days). This applies even if you canceled your scores on a test taken previously. If you take the paper-delivered GRE revised general test, you can take it as often as it is offered.