Sending a thank you note is one of the most important things you should do after your interview concludes. According to Erik Bowitz of Resume Genius, following up is “not an option; it's an expected courtesy.”
You don’t need to pull out a formal thank you card; a simple email will suffice. Thank the hiring manager for their time and include something specific, so it doesn’t feel like a generic thank you note. Include any details that will reassure the hiring manager you were engaged in the interview and are enthusiastic about the position. "In addition to expressing your appreciation, you might include a follow-up thought based on a particular interview question," says Studner. "And be sure to state that you look forward to the next step in the process."
But how soon should you send a thank you note? John Turner, CEO of UsersThink, says you should send the note within 24 hours, but wait at least 1-2 hours until after the interview. “Even if they don't hire you, it will help them remember you, and you never know when they might recommend you to someone else,” says John.