Since I became a fan as a young child I started my fandom grew as I did and thus developed incrementally begining with football, adding basketball later and then baseball after that. Not only that, since it was a childhood thing its hard to pinpoint specific dates but I will give it a whirl. The three coaches at the time when I definitively remember being a fan of any sort were Shira, Davis, and Gregory. The coach of each sport when I recall starting to follow said sport were Shira, Greene, and Polk. If you add WBB its Shaefer.
With that said, I have never rooted for any other program in any sport other than MSU and I am for MSU in whatever we participate in although there are a number of sports that I have never followed and could tell you very little about.