After an interview with a really great candidate, my clients usually want to hire that person on the spot. They do not want to wait. They feel very strongly that they have waited long enough, and they want to get this person on board ASAP. While I completely understand their desires, I ask them to think about the interview for at least 24-48 hours. The reason for the waiting period is that your thoughts are really different outside of the interview, especially if you give your thoughts a chance to simmer. Think about it like you think about soup in a crock pot.
Similar to making a soup where you initially collect and prep all of your ingredients, a company preps by putting together an ideal list for the best candidate, writing a job description, writing a job ad, and posting the job. The job then simmers on the job boards as applicants begin to submit resumes, compared to the soup simmering in the crockpot. Then, the employers get the resumes and begin interviewing, like adding spices to the soup, continuing to let it simmer.
Throw in some vision and dreaming, your crock pot will make some pretty great soup. Eat the soup too early and the spices may have not soaked in yet. If you wait too long, the vegetables turn to mush, and the soup is not as good.