The process involves taking impressions of your mouth while your teeth are still present. Models of your mouth are then produced. Your clinician can then do simulated extractions on the models and place the denture teeth as close as you require to your natural setting and correct many things about tooth position that you may not be happy with at present.
When your teeth are extracted, your new denture is ready to be inserted by your dentist. In this way you never have to walk around without teeth.