Wall of text incoming. I'll go two situations. One where I wake up in Equestria as my favorite pony, and the other where I wake up on Earth. I'll start off if I'm on Earth. The pony I would be is Rainbow Dash. --- I would wake up like any normal day. My annoying alarm would go off, and I'd hurry to shut it off. However, upon doing that, I would notice there's something different. Knowing me, I'd try to ignore that, and struggle to shut off the alarm first.
After I manage to shut the alarm, I would be pretty frightened. I'd most likely look at what would be my light-blue hooves, and be mixed with confusion, panic, excitement, and fright.The first thing I would do would be run for a mirror, however I have no mirrors in my room. With the exception of one tiny shard of a mirror, and a small hand mirror I would have to open up. All the while muttering random curse words and wondering what the hell is going on. I would try and calm down, and probably lay on the bed. I'd stay there for a few minutes, trying to recollect my thoughts, and possibly piece together what is currently going on. At the time my alarm goes off, no one who is currently in the house usually isn't awake. I'd carefully exit my room, and cautiously enter the bathroom, the closest place and best place with a decent sized mirror, and privacy. I'd close the door, and lock it obviously. I'd probably be shaking throughout all of this too, being shocked. I'm not sure if I would be tall enough to see myself on the mirror, being I'm a pony, so I'd may have to climb up on the counter to see myself. Once I do see myself, I would start to hyperventilate, and panic.
Seeing myself as Rainbow Dash, I would most likely believe this is a very lucid dream. I personally gave up on believing anything like this ever happening, so if it were to happen, I would probably think it's a dream. I'd then try to do tests, to see if this really is a dream. Splashing my face with water, or anything to see how I would react, depending on how real everything felt. Eventually I would come to the conclusion that this is real, and I would begin to panic more. I'd be confused, worried, scared, everything. Thoughts would be running rampant in my head. "What's going on?" "How will everyone react?" "What happened to the real Rainbow Dash?" "Why am I even a pony to begin with?" After awhile I'd try to calm down, laying down on the ground, and trying to relax. Although this probably wouldn't work, one question would be constantly nagging me. "What do I do now?" Now I'm a pony, Rainbow Dash to be specific, on Earth. I'm the only pony there, not to mention LOTS of bronies have huge crushes on the pony that I would be. Including myself. I'd have to obviously tell my family, as there's really no way I can keep something like that a secret. At least to them. I'm not sure what their reactions would be, but they should be good enough to where I would be kept a secret, as long as possible, as everyone tries to figure out what to do. After my family gets over it, (I'm just going to say it's a Saturday.) I'd probably would've calmed down by now. I'd have the rest of the day to get used to my new body. Which most would be spent in the bathroom examining myself, for most likely hours. Testing out my new limbs, including my wings, (As much as I can in that cramped space.) and everything else. Everything. :/ I'd be a different gender, so things would most likely get pretty awkward. Other than that, the rest of the day would be spent getting used to my used body, and figuring out what to do next. I'm not going to go on to what would happen the following days. --- If I was on Equestria, things would probably be the same. I'd wake up, go through the mix of emotions, being confusion, panic, fight, excitement, etc. Go into the bathroom, see myself in the mirror, etc. After I get through the shock, I'd eventually find out I'm in Equestria, and would become wildly happy, once I realize this isn't a dream. I hate living on Earth. I'd most likely spend a hour or so getting used to my new body, self examination, all inside of my house, obviously due to privacy reasons. After I get past that, I'd fly around Ponyville, noting how epic that would feel. I'd go and meet everyone, and would most likely live as Rainbow Dash in Equestria, for the rest of my life. Every day afterwards, most likely being infinitely better than every single day I've had on Earth. Alright maybe not every, but close enough. --- That's pretty much sums it up.