Why do I always (do something)?

This is a phrase that people use when they want to complain about their own bad habits. You ask this question when you try not to do something, but you feel like you don't have control. It's usually used around friends or family members.

put (something) off until (some time)

When you "put off" something that you're supposed to do, it means that you wait to do it later. People often put off doing things that are boring, difficult, or stressful.

You can use the phrase "put ___ off" by itself:

A: Have you bought Renee a birthday present yet?

B: No, I've been putting it off.

Or you can use the phrase "until ___" to express when you will or have started doing it:

Don't put off doing your taxes until the week before they're due.

the last minute

The phrase "the last minute" is a common way of describing doing something just before the deadline. Of course, it doesn't literally mean the last minute before the deadline. In the case of the assignment described at the top of this post, "the last minute" means two days before the assignment is due.

If you really want to emphasize how close to the deadline you are, use "very" before "last minute":

I waited until the very last minute to turn it in.