You have to implicitly answer "why now" when prioritizing a task among all the other things you could do.

There are two very good answers to this:

1) "because it just happened and it's fresh in my brain"

2) "because there is an external deadline coming up and I'm obliged to."

People prone to procrastinating work best under the latter.

But if the task is small, will definitely need to get done at some point, and it just happened, just do it now.

If you don't it will linger and fester and be thrown on top of an ever-more amorphous, ugly, intimidating pile that will take heroics to fix.