Right. Therefore it is better for both the employee and the employer that you fire people in the first few days if you do not feel comfortable with the worker.

Right. Therefore it is better for both the employee and the employer that you fire people in the first few days if you do not feel comfortable with the worker. The employee can just continue their job hunt, and you will not spend so much on getting clear on the fact that this person does not fit. And if a few days strikes you as being too short, then try a week or two. Personally the only time I fired someone that was just not suited, was after two weeks. But in thinking back on it, I already knew this aftera few days, just needed some time, and some conversations with the employee to convince myself. Of course, part of that decision was that the conversations did not lead to improvements, but the important take away is to act fast on your hunches. If you don't trust yourself to fire someone after 3 days then at least set up some tests that will provide you with the data to know whether or not the employee will work out. It is better for everybody that way.