Hello Aspirant,

It is clearly written in the instructions that incomplete application will be rejected so if you have submitted your application to VIT without your class 12th marksheet then your application might be rejected by the time but however I would recommend you to check your application status once if it is cancelled then you can make direct contact through mail to the competent authorities if you have any genuine reason for delay but if it is normal and you are getting the option to upload the marksheet (which might not be there because the last date for application is August 2nd)  then don't wait for it.

I hope this information helps you.

Good Luck!!