Formula indicating employees entitled to a salary increase every three years from date of appointmen

[Marcia]

There is an agency policy that every 3 years from the date of appointment or promotion, an employee is entitled to a percentage increase in his/her salary. If I use conditional formatting, what is the formula that will mark all employees that will receive increases during the year 2019? Say, Col A contains the names of all employees and column B contains the date of their appointment.