When you're starting a new job or in training, be sure to show an uncanny ability to focus. Prove that you can spend stretches of time on a single task, and that your efforts produce a high yield. You're not just showing off, you are exemplifying how you will work when no one is watching.
It's also a good idea to put your best foot forward. Unless there is an emergency, many, if not all other things can wait for a stopping point in your work day. Learn quickly, work diligently, and strive to prove your worth.