I doubt they'd care, assuming they'd even know what a brony is. So, not much point in telling them at all. I'm still pretty well reserved and keep all these ponies a secret
I'd likely talk to Twilight, or likely Pinkie (both seems like they'd be the first to recognize a new face in town, or the portals magic, and stalk me down). Staying, perhaps, since I've not that many friends irl :/