Why do we wait until the last minute to complete things? If we know three months in advance, why wait until there are 3 days to go? Just in time solutions are fine for supply chains. However, they are not ideal for getting items off your to do list.
When assignments at work, at school, accounting, tax or financial matters often seem to be done at the last minute and not weeks in advance.
My ideal situation for these things is to do the work when it is available to be done. This means when the assignment is handed to you, get going on it. It does not mean throw it on top of a pile of papers or in a drawer and forget about it. Receiving multiple red font alert-type letters is not a sign of a well organised operation.
I understand it can be challenging. I know other things come up and take your focus away. And it can be difficult to juggle many balls at once. However, start making it a habit to deal with things as they come up. Make plans and put the time required in your diary.
Just in time solutions can work but ahead of time is usually even better.