Do I know my GRE scores when I choose to send them on test day? I haven't started preparing for the GRE and I have my exam in a week's time (15th Oct.). I know I'll get a low score which is why I don't want to report the score to any university. So, I have two options:


Reschedule the exam to something like 10th Nov.
Take the exam on 15th Oct. and take it again after 21 days.


I will go with option two if reporting the scores is optional after taking the exams since reporting the score is my only fear in regard to my question.

Do I have to report my score when I take the GRE? Do I know my scores before I choose?
When you finish the GRE, at least a computer-delivered GRE, you will be asked if you want to report  or cancel your scores. If you choose "cancel," you don't get to see them or report them. If you choose "report," you get your unofficial scores, then are asked to report them.

According to ETS (emphasis added):


  On test day, after completing the test and viewing your unofficial Verbal Reasoning and Quantitative Reasoning scores, you will be asked to designate which score recipients you want to receive your General Test scores.


At this point, reporting is optional, you don't have to report to anyone at this point. 



As for whether you personally should reschedule or retake it after 21 days, that's a question we can't answer, but hopefully this information helps you decide.