Should we fill slots earlier or later in competitive exams like VITEEE and BITSAT ?

dear nanny 
that depend upon your comfortability , and time . 
there are no issue if you choose that earlier or later also , the ques sets will be diffrent everytime . 
so, fill it as soon as possible , so, that you can concentrate on main exams , thats jee advanced , (in case you qualified jee mains ) 
regards 
kindly approve