Times have changed and the days of working your entire career at one or maybe two companies has all but vanished from the world. Today's typical employee is on the move, changing jobs and sometimes entire careers on a regular basis. In today's business world, you aren't necessarily rewarded for dedication to one company and the reality is that if you stay in job too long, you could actually be hurting your career in the long run. Let's take a closer look at the time frames that are used to measure a potential employee's success or failure with a company. As a rule of thumb, the numbers that should be remembered are 8, 18, 48 and 72.

Eight Months
Our first number, 8, is the first number potential employers will look at when examining your resume. If you have stayed in a job or eight months or less, this is often viewed negatively by companies considering you as a potential candidate. This time period suggests you didn't pass your six month review or you simply didn't give the job a fair chance.

Eighteen Months
The magic number 18 is the minimum acceptable length of time you should stay with your current company. This time period suggests that you survived not only the six month review process but also the annual review process as well, indicating that the company you are working for sees you as an asset. Anything less than this number may be looked upon with scepticism unless you were downsized by the company.

Four Years
Four years (48 months) is the amount of time you need to spend working for a company to receive "full credit" for your work. This assumes there aren't any glaring signs of stagnation during your time with the employer. If, during this time you continued to receive more and more responsibilities and even a few job title changes along the way, your employment time with the company will be looked upon favorably by your potential employer.

Six Years
If you spend six years (72 months) or more with a company it can begin to start hurting your career especially if you aren't continuing to receive promotions or increasing responsibilities with the company. A stagnate six or more years may appear to your potential employer that you are unambitious and while not necessarily expendable, thoroughly mediocre at best. However, if you continue to receive more and more responsibilities and have earned several promotions along the way you are free to stay with a company for as long as you like.

It's important to consider the time you have worked for a company before you decide you should move on. Leaving too soon could hurt your career, with potential employers believing you didn't give the company the proper chance or weren't able to cut it after the six month review process. However, staying too long can make it seem as if you are unambitious or are only a mediocre employee, instead of giving you the boost of loyalty that you might think you deserve for staying as long as you did. Following the accepted timelines when changing jobs can give you a significant advantage over other applicants so you can find the perfect job for your talents.