I Had the Zoom Teeth Whitening Done by a Dentist a Week Ago, How Long Before I See Results?

Immediately!  If you did not get the results you were expecting you should use some take home trays to follow up.  Some people's teeth will not respond well to the one visit procedure and very few will achieve their maximum color change in a one visit procedure.  Repeated applications of bleach over time will give the most predictable results.

Your teeth will be the whitest they're going to get immediately after having the ZOOM done in the office. If anything, they will tend to dull with each passing day.

I am afraid you have all of the results you are going to see unless he or she is making you a set  of take-home trays so you can continue bleaching at home.  Zoom doesn't always produce the results everyone expects.  You should have a clear conversation with an ethical clinician before doing zoom.  Some people I won't do it on, because my experience has showed me that for particular colors and tooth shade ranges results are minimal.