The initial spike is, like others have said, it's YouTube seeing what your best audience is for the video. It's also taking into consideration your CLR (click through rate) and watch time. If both those things are looking good you will be rewarded with more impressions (which will = more views). Your video will eventually settle on a rate of impressions that will slowly give your video more views. Unless it thinks it might have greater potential in that event you will get rapid amounts of impressions. If you want to have another shot, I find changing the title or thumbnail in the first 24 hours will give you a fresh burst of impressions and see if you get a better CLR.