MIM now or MBA later?

If your goal is marketing or brand management, you should by far see more benefit from the MBA degree. Top companies all recruit for brand and marketing managers at the better MBA granting institutions--it's essentially the "go-to" place for talent for them. They do not recruit as actively with MiM programs, so you would be a bit more "on your own" when the time arrived for job search. Plus the extra work experience will make you more valuable to your potential employer and also provide more experience for you to draw from in the classroom to benefit discussion and project input, etc. I admit I am biased towards the MBA, but it is for good reason--it's more marketable and over the long term, more bankable for your career.