So much of our success as actors comes down to time-management. Casting Directors and other industry professionals take in to account your ability to be where you’re meant to be WHEN you’re meant to be there.
When you’re submitting yourself for auditions on websites such as Actors Access and NYCastings.com/Casting Networks (etc) the audition/rehearsal/shoot dates are usually posted on the breakdown. It’s important to make a note of these dates and make sure your schedule isn’t in conflict. If it is, it is wise to make a note of any conflicts in your submission.
Also, as far as auditions/callbacks/bookings go they generally take longer than you think they will. If you have an audition appointment at 10:20am, say, and have something else scheduled at 11am, you should be aware that the likelihood of your making that later appointment on time (or at all) is slim. In this case it would be wise to alert the later booking of your potential lateness as soon as you know about it (not 10 minutes before you’re meant to be there).
When scheduling an audition it is completely reasonable to ask for another time-slot if you know you have a conflict. You may not always get it, but it can help you avoid a sticky situation.