Just show up for work and make out that you have the job. By the time they work it out you will already be a vital cog.
I wonder how ling it would take them to notice that they didn't hire you. lol
Depends on a lot of factors. Every company is different and it also varies with the level of the job you are seeking. The company I work for, which shall remain nameless, is an extremely large global corporation. They are notoriously slow in the hiring process, which often gets dragged out to six or nine months in length for management level personnel. Even the hiring managers complain because it takes so long to fill critical vacancies.<br />
Write a thank you note immediately following your interview and before you leave the interview, ask each interviewer (a) how you did; (b) what is the next step in the process; and (c) how long before I can expect to hear something.
If they tell you to call back in five days. You call in three! If they tell you that they will respond in two days, and they don't call the next day to remind them. This way they can tell you they found some else. Usually, that's what happened. Don't give up I have landed a job for calling the next after they hired someone. The person they hired quit or overexaggerated their resume. They called me back because they knew I wanted the job bad enough to call after they didn't respond. Just follow through on the calls until they tell you they hired. Good Luck!
I ask them when they expect to make a decision, which is usually in a week's period.