It can be really hard to manage your time at university. Making sure you're attending everything, doing the reading, keeping up with extra curricular activities, and experiencing the wilder side of university can be a lot to deal with. It's inevitable that you will end up leaving assignments or revision until the last minute on the odd occasion.
While chugging energy over a 3,000 word essay might be part of the university experience, I promise you it is not fun. You'll get better grades if you're more prepared, and you can hand your essay in early and spend the night celebrating. It's a good idea to work on your assignment for at least 10 minutes a day every day until the last couple of weeks before it's due. This might not sound like much, but the minutes add up. By the week before your essay is due, you will have spent so much time mulling over your approach and playing around with ideas that you'll have a more convincing and thought-through final piece. The same advice is true for lab reports, exams, and other forms of test.