It really depends on your insurance. I had seminar, pre-op consultation, labs, 6 months of weight management with my PCP, a psych eval, cardiologist clearance, endoscopy. Then I will have another set of labs and a pre-op consultation that's on the 19th of this month and a 2 week full liquid diet starting 11/27.
Make sure you really have them spell everything out for you. Ask tons of questions even if you think they are stupid.