Hii Amar! roll number alone will not help find out the result you need to mention which state or national board class 8th result you are talking about. But I will suggest you to visit the official website of your school for checking out exact date of result declaration. You can also visit your school offline for result related clarification.

Secondly if your state conducts a board exam for class 8th then you can find it out on your respective State board official website.

Thankyou!