Don't wait to send a thank-you note. Send it right away -- no later than the next day.
Experts disagree, however, about whether to send the note in an e-mail or to send it in the mail. Some say that e-mail should be a last resort. These experts maintain that a letter sent via mail on quality paper is best. But speed is important, so they recommend sending it express so that it arrives the next day [source: Darlington]. Others are not so stringent and believe that some employers actually prefer e-mail. And still others say to send both. A survey showed a pretty close split between what format employers prefer [source: Haefner]. For hard copies, you also might want to write out the letter by hand to make it extra personal -- but only do this if you have excellent handwriting [source: Farr].
Although every thank-you note should be personalized to the job and the interviewer, we'll explain a recommended structure. The salutation should use a last name, unless the interviewer explicitly allowed you to use a first name. The note should be brief -- about three short paragraphs. The first paragraph thanks the interviewer for the opportunity and his or her time. If you can, throw in a reference to something discussed in your interview that might help the interviewer distinguish you from others [source: Darlington].
The second paragraph should include some subtle and gentle reminders of your qualifications while reiterating your excitement for the job. This paragraph can also include anything you forgot to mention. Finally, the third paragraph can give thanks again and offer something hopeful, like "I look forward to hearing from you." Throughout, the tone should be professional, but warm.
Now that the thank-you note is all finished, it's finally time to sit back and wait. Although this might be a stressful time for you, it would be a mistake to pester the employer about a decision. However, if the interviewer gave you an idea when the decision would be made, and that time comes and goes without a word, it would be fine to send an e-mail politely asking how much longer you should expect to wait.