I have had my Chili Red MINI Cooper S for about 4 and 1/2 months and I really want to keep it looking as nice as I can for as long as I can (although I don't think I can be as devoted as some

).
I want to know when I need to start waxing my car after I wash it? Or, to put it another way, how long does the finish from the dealer actually last?
Also, I have a vinyl Union Jack flag on the roof and I want to know how to take care of it. Should it be waxed with the rest of the car? Is there another treatment I should be doing?