Should I take my inhalor before I go in to see the doctor for a check up?

Depends. If you are not in any respiratory distress you should try to avoid using a rescue inhaler such as albuterol at least 4 hours prior to the visit so the doctor can hear what your lungs sound like.
Yes. If you feel the need to use your inhaler because you feel short of breath then by all means use it. If however, your symptoms are not so severe that you would normally use the inhaler (if you weren't going to the doctor) then don't. Your doctor would rather have an accurate sense of your baseline than assume that your asthma is better controlled than it is because you treated prior to the visit.