You may get a scan or set of impressions done which will be sent to Invisalign. Your experienced dentist or orthodontist can at least give you a flexible estimate of the time the treatment will take as well as how many trays they expect you to need. Again, this is just a first visit and not a comprehensive plan. But it can be great for helping set up expectations for the future. Rough estimates may not be exact, but it certainly gets you on track.