Here's some SOUND advice from someone who works in the dealer world, MERCEDES...when you buy a car or lease or that matter...have the dealership set-up the tinting because they should have a shop they use regularly and that shop works on their cars a lot...so they know what to watch for and if there are any issues it will be handled IMMEDIATLY because there is no chance of YOU doing it, it happened prior to you taking delivery and go over the car like your life depended on it.
Going through the dealer for tint is a great way to pay nearly double what tinting costs. Tint shop makes their money, and dealer takes their cut for doing... nothing really.
Laughed at the dealer finance man when he tried to tell me it would be $500 to tint my car. ONLY $8 a month more, or something like that.