When to Call or Write People
People are generally freshest during the morning, so try and make your calls at this time. Try to avoid calling business people on a Monday morning or a Friday afternoon. If you cannot get past the receptionist/secretary who is 'guarding' their boss, try calling early in the morning (before 8:00 a.m.) or late in the afternoon (after 5:30 p.m.), when the receptionist/secretary is less likely to be in the office.
If you are going to call someone after sending him or her a letter, try and ensure the letter arrives on a Monday or Tuesday, then you will be able to call him or her later in the same week - while they still remember your letter.