You begin setting up your changes. You set the Chronivac to make the change take place over a week. The idea of your body slowly altering, allowing you to witness all of your newly forming anatomy, and even the growing instincts of a crows mind, while feeling your human thoughts and capabilities fade into nothing was deeply exciting for you. You set the duration to two months, hopefully allowing you to get the full experience in while not being gone for too long.
Speaking of which, he set the reality alteration settings to "on", and his awareness to off. This would be like a vacation for Alvin. He would be gone for a while, but not have to worry about returning to humanity without a job due to absence. He would be able to come back into work, seemingly without missing a beat. This would also cover the week of time it would take for the transformation to finish.
Alvin's final change was to make the transformation pleasurable. He knew that the transformations from the Chronivac were advertised as painless and risk free, but Alvin saw no reason to not give himself the most pleasurable experience possible.
Satisfied with his changes, Alvin pressed "Begin" and felt a wave of euphoria wash over him. While the changes were set to take long enough to not immediately be visible, Alvin swore he could feel his body shifting. And it felt great.
Alvin stood, and made his way to his bed, feeling a growing erection between his legs. Alvin wasn't prepared for the arousal that would come with this pleasure setting, but he was certainly not regretting it. He laid down on his bed spread and took off his pants and boxers, not even bothering to get under the covers. Alvin began to stroke his hard penis.
Alvin's thoughts began to become sexual. He thought of beautiful women his found himself attracted to, and watched in explicit videos online, but as he continued, he found that he was thinking less of them, and more of crows. Not the one he was becoming, but the idea of rubbing his eventual cloaca against the wet, swollen, and dripping cloaca of a female crow was *Very* arousing to Alvin.
Alvin continued to rub. He had never thought about birds sexually before, but knew this would likely happen if he changed his mind. And he wasn't hating it. He was becoming a crow after all, why should he feel shame about his new forming attractions.
Alvin soon came, and began to breath hard. He looked out the window, seeing it was night, and decided to sleep. He would check his changing body in the morning.
So Alvin fell asleep, excited to see what would be different in the morning.