Elsa,
I agree that Monday is the best day to terminate an employee. I also believe in having another person in the room, preferably from HR. They can then deal with the "what happens next" questions. If the supervisor has made an honest effort to help the employee improve their performance, the dismissal should not come as a surprise. If the dismissal is for reasons other than performance, then policy should establish the appropriateness of the action.
Pat
